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The Hormones of Hunger

January 29, 2013 in Hormone Regulation

I want to delve into the effects of diet and lifestyle on hunger and satiety signals in a series of upcoming posts. I am mostly interested in the hormone dysregulation that occurs during metabolic syndrome, but also in how to optimize diet, exercise, sleep and stress management to achieve an ideal weight.

The feeling of hunger is regulated by a complex system of hormones that interact with neurotransmitters and neurotransmitter receptors within the hypothalamus region of the brain. These hormones essentially activate or deactivate specific neurons in the hypothalamus that control hunger. These neurons have receptors to Neuropeptide Y (NPY), the essential neurotransmitter in regulating hunger. The hormones can increase or decrease hunger either through binding the receptors for NPY or increasing or decreasing NPY itself. Essentially a hormone will increase hunger if its expression activates these NPY neurons whereas you will feel satiated if a hormone’s expression deactivates the NPY neurons. The interplay between these hormones and your brain is complex and only partially understood. However, what scientists do know about these hormones can help inform our decisions and compulsions regarding diet and other lifestyle factors.

New hormones continue to be discovered and their roles in regulating appetite, satiety, metabolism and digestion continue to be studied. As the full list of hunger hormones grows, understanding the complex interplay between these hormones, the types of food you eat, and the amount of muscle and fat on your body quickly becomes overwhelming. I have tried to summarize the key players (at least as scientists currently understand them):

Hormones that tell your body you’re satiated:

Cholecystokinin (CCK) is secreted by the cells that line the duodenum (the first segment of the small intestine) when they detect the presence of fat. This causes the release of digestive enzymes from the pancreas and bile from the gallbladder. Increased levels of CCK signals to the stomach to slow down the speed of digestion so the small intestine can effectively digest the fats. CKK is also a neuropeptide similar to NPY and has a direct action on neurons in the brain to signal satiety. This is the most immediate hunger suppressing signal and is the reason why eating fat with your meals is so important.

Oxyntomodulin is released in response to protein and carbohydrates in the stomach and signals a change in energy status to the brain. Oxyntomodulin enhances digestion by delaying gastric emptying and decreasing gastric acid secretion.

Peptide YY (PYY) is released by cells that line the jejunum, ileum (the next two segments of the small intestine) and colon in response to feeding and is especially sensitive to protein. PYY signals to the gallbladder and pancreas to stop producing digestive enzymes. PYY is important in increasing the efficiency of digestion and nutrient absorption after meal by slowing down gastric emptying, slowing down the speed of digestion, and increasing water and electrolyte absorption in the colon. PYY interacts directly with NPY receptors in the hypothalamus in an inhibitory fashion, thereby turning off hunger signals.

Glucagon-Like Peptide-1 (GLP-1) is secreted in the ileum in response to carbohydrate, protein and fat. It rapidly enters the circulation and is one of the fastest and shortest-lived satiety signals. It inhibits acid secretion and gastric emptying in the stomach. GLP-1 also increases insulin secretion and decreases glucagon secretion. GLP-1 decreases hunger signals by reducing the amount of NPY.

Leptin plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. Leptin is released both by adipocytes (fat cells) and by the cells that line the stomach, so it signals both that the body is fed and that there is sufficient energy storage. This appetite inhibition is long-term, in contrast to the rapid inhibition of eating by CCK and the slower suppression of hunger between meals mediated by PYY. Leptin both rapidly inhibits NPY production and deactivates NPY neurons in the brain to signal that the body has had enough to eat, producing a feeling of satiety. It is one of the most important adipose derived hormones (read more in this post).

Adiponectin is secreted from adipose tissue into the bloodstream where it signals decreased gluconeogenesis (when the body converts fats and proteins into glucose for energy), increased glucose uptake, lipid catabolism (breaking down of fats), triglyceride clearance (storage of fats), increased insulin sensitivity, and control of energy metabolism. Adiponectin acts directly on NPY neurons similarly to leptin but with additive effects.

Hormones that tell your body you’re hungry:

Ghrelin is considered the main hunger hormone. It is secreted by the cells that line the stomach when the stomach is empty and also by the pancreas when it detects low blood sugar. Also, the liver secretes ghrelin when its glycogen storage runs low (and glucagon is high). When ghrelin is released into the circulation, it directly activates NPY neurons to stimulate appetite. Increased levels of ghrelin are directly associated with the sensation of hunger. It is considered the counterpart of the hormone leptin. Importantly, ghrelin is a potent stimulator of growth hormone (GH) secretion and regulates nutrient storage, thereby linking nutrient partitioning with growth and repair processes. Ghrelin activates several anti-inflammatory pathways in the body and promotes cell regeneration thereby promoting healing, especially within the gastrointestinal tract. Ghrelin regulates glucose homeostasis through a direct action on the pancreatic islet cells (the cells that secrete insulin). It is also important for memory function and gastrointestinal motility.

Cortisol is well-known as a stress hormone, but it has key roles in regulating metabolism and hunger. Cortisol levels determine whether the body uses glycogen stores or triglyceride stores for energy (stored carbohydrate or stored fat). Cortisol can also stimulate gluconeogenesis, the process of converting amino acids (proteins) and lipids (fats) into glucose in the liver. It is believed that cortisol directly influences food consumption by acting on NPY neurons in the brain as well as affecting the levels of NPY and leptin. Cortisol seems to have a particular effect on the desire to eat foods high in fat and sugar. This is why stress management (which really means controlling any factor that might mess with your natural cortisol levels) is so important.

Glucagon is a hormone secreted by the pancreas when it detects low blood glucose levels (typically between meals, but this can also happen as part of that “sugar crash” after eating something very high carbohydrate). Glucagon signals the liver to convert stored glycogen into glucose, which is released into the bloodstream, a process known as glycogenolysis. When glycogen stores are low, high glucagon levels drive gluconeogenesis, the process of creating glucose from amino acids and fatty acids. Increased glucagon amplifies the hunger sensation.

Insulin is secreted by the pancreas in reaction to high blood glucose levels (for more on insulin, see this post). Insulin causes cells in the liver, muscle, and fat tissue to take up glucose (and fatty acids in the case of adipocytes) from the blood, storing it as glycogen. While insulin is released as a result of eating carbohydrates, it paradoxically increases hunger as opposed to decreasing it. This is caused by direct action on the NPY neurons and is the reason why eating a carbohydrate-rich meal is not as satiating as eating a meal that includes fats and proteins. It also explains how quickly we feel hungry again after a high-sugar snack.

These hormones have important roles both in regulating aspects of digestion and signaling to the brain whether or not you need to eat. Many of these hormones are also critical in regulating your blood sugar both after a meal and between meals (fed and fasted states). Some of these hormones also affect other systems in the body, for example, interacting with the immune system and controlling inflammation. Understanding how your diet and lifestyle affect these hormones will help you make choices that regulate these hormones properly, allowing yourself to listen to your hunger cues and trust that your body knows what it’s doing. And regulating hunger hormones is a key part of healing and being healthy.

Tags: adiponectin, amino acid, appetite, carbohydrate, cholecystokinin, CKK, colon, cortisol, digestion, duedenum, eat, Fat, full, ghrelin, GLP-1, glucagon, glucgon-like, gut, hormone, hunger, hungry, ileum, insulin, intestine, jejunum, leptin, lipid, meal, metabolism, oxyntomodulin, paleo, Paleolithic, peptide, peptide-1, Protein, PYY, satiety, stomach, Sugar, why, YY
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My 21-Day Sugar Detox Experiment: The Good and The Great!

January 23, 2013 in 2013, Sarah's Personal AI Struggles

Somewhere around Day 16, it felt like an eternity. But here I am, all of a sudden, done my 21-Day Sugar Detox experiment. And what a valuable and educational experiment it was!

If you recall (from this post), my goal was to test whether or not the hefty amount of fruit (and much less hefty but still present amount of honey, maple syrup and coconut-based baked goods) was perpetuating inflammation in my body and slowing down the healing process. I have an autoimmune disease which is healing slowly on the autoimmune protocol. I have a mild case of SIBO, which means starchy vegetables and high insulin fiber content foods are out (yes, that should have meant coconut flour was out and yet I often found an excuse–and it always set me back). Really, my eating was pretty clean going into the 21-Day Sugar Detox. Even through the holidays, I was doing a very good job sticking to the autoimmune protocol, but I have been using fruit as a crutch, eating 5 or 6 (sometimes more) servings per day.

So, for me, the 21-Day Sugar Detox wasn’t about reigning in bad habits. I hadn’t fallen off the paleo bandwagon. My eating was not crazy. I was just enjoying fruit with every meal. And sometimes snacks. And sometimes before bed. That’s not necessarily a bad thing. I am not part of the anti-fruit paleo camp. And even though I lost most of my weight following a low-carb diet, I’m not even part of the low-carb paleo camp (I understand much more about the relationship between what we eat and hunger hormones and inflammation and weight loss now, see this post for a bit more on leptin). By the way, I’m also not in the “safe starch” paleo camp. I’m more in the “find what works for you” paleo camp. There are so many ways our different bodies react differently to fruit and starchy vegetables and there is a huge amount of individuality in terms of both tolerance of and need for these foods–I believe it would be foolish of me to recommend one prescription for everyone. Without a doubt, eating 6 pieces of fruit a day is not bad for everyone. Many others could eat that much fruit and be optimally healthy. Of course, many others could eat a sun-dried tomato and bell pepper omelet with a cup of coffee dressed with grass-fed heavy cream for breakfast too. Sadly, not me. Sigh.

So, how did I feel following the 21-Day Sugar Detox? Check out my updates for week 1 and week 2. Looking back on all three weeks, the first week, I really didn’t notice much difference other than the fact that my skin was doing some weird things. I realize now, that that was a bit of a detox reaction because my skin cleared up dramatically in the second week. Then, I had some fresh coconut on days 15 and 16 and had a very dramatic reaction to it in the sense that I had the worst acne breakout I’ve had in months. And I didn’t even eat that much! So, I have finally accepted that whole coconut is not good for me, dangit. The bright side? Getting my diet so clean during the detox allowed me to finally identify coconut as a trigger without any room for doubt. That knowledge is very valuable for me–even though the actual fact of being sensitive to whole coconut (on top of everything else) can be described by a variety of inappropriate consonant-heavy words. At least the acne seems to be healing quickly.

Aside from acne, I noticed some extremely dramatic improvements in my mental clarity, which started in week 2 and just keeps getting better. This is important for me (especially given the BIG announcement tomorrow). I would never have described myself as suffering from brain fog before, but now that I see just how much more productive and efficient I am and just how much quicker I seem to be able to think, it’s obvious that sugar was impeding my mental processes. I also feel like I’m sleeping better and waking up feeling more rested, which again, I would never have described my sleep quality as lacking beforehand. I also feel like my energy levels are better (and following the healthy pattern of waking up with energy and then gradually running out of energy throughout the day until bedtime).

I also lost 4 lbs during my 21-Day Sugar Detox, 2 lbs in week 2 and 2 lbs in week 3. Weight loss was not one of my goals, but this makes me happy anyway! I actually think that the majority of this weight was bacterial overgrowth (although my body fat percentage did drop too, so maybe it’s a bit of both). I say this because I also have noticed a pretty dramatic reduction in bloating in my abdomen. There I was thinking that my abdomen was hard because I was getting so muscular. Nope, that was SIBO. But, it totally rocks to see that bloating resolve and see the scale move in my favorite direction. I wish I could show you before and after photos (like Stacy of Paleo Parents did! Wow!), but I didn’t take before photos. Suffice it to say, that my I’m fitting into my smallest pants comfortably again and several people who know me well have commented that I look like I’ve lost weight (actually, they started commenting before I technically did lose any weight too!).

I also want to point out here that many people have commented that my meals are huge. They are! And I’ve lost weight! I’ve heard that many people have a tendency to under-eat when they tackle the 21-Day Sugar Detox, or the autoimmune protocol, or if they just want to lose weight. It’s extremely hard for your body to heal and/or lose weight healthily if you are not providing it with enough nutrition. Reducing food intake too much increases cortisol and makes it impossible to lose weight; it also messes with leptin. Eating enough is really important and I hope my meals have helped provide some guidance, both in terms of portion size and in terms of just how many vegetables I eat. That’s another thing that happens when people tackle the autoimmune protocol–they get so scared of starchy vegetables and FODMAPs that they eat very little vegetable matter. Vegetables are important for healing and even if variety is limited (even if some people have a hard time with raw veggies and can only digest them well when cooked), it’s important to remember to eat enough of them! (I will refer you once again to Dr. Terry Wahl’s TedX talk here)

I never experienced a carb flu (although I have caught my daughter’s cold, but I hardly think that counts) or headaches or severe energy crashes–probably because the difference in total carbohydrate intake for me wasn’t as dramatic as many people who tackle the 21-Day Sugar Detox. I had a few days where I felt resentful and begrudged not being able to partake in treats around me, but I got through it. I had a couple of evenings where I felt snacky and normally would have indulged in a bowl of frozen fruit, but avoided the temptation by just going to bed (that’s usually the eating to stay awake bad habit that I still battle from my long years of obesity and metabolic derangement). Let me just add here that yes, I do still sometimes get sick and no, that is not a statement of my diet and lifestyle (unless I am seriously that sensitive to skipping bone broth for few days!). I get sick way way way less often than I used to, don’t get anywhere near as sick as used to be typical for me, and get better much more quickly. But, I do have a dysfunctional immune system due to my autoimmune disease and I expect to always be a person who does catch at least some of the colds and flus going around, especially while living in the petri dish that life with young kids is.

Okay, so the real reason for doing the 21-Day Sugar Detox was to see if it would make a difference to my autoimmune disease. And WOW! Did it ever! Below are before and after photos. Now, the before photo was actually taken two months ago, right before I realized that chocolate was a problem for me. I did see improvement in my lesions after cutting out chocolate and then things stabilized again over the holidays (probably because I was eating coconut and so much fruit). So, not all of the difference between before and after can be attributed to the sugar detox, but more than half of it can! (The detox amateur that I am, it never occurred to me to take before and after photos of how I look or my lesions right before starting, so you’ll just have to take my word for it…. I’ll do better next time, I promise!)

Pretty dramatic, right? Every one of those red, raised, scaly lichen planus lesions were very itchy and painful in November. What is still healing and visible now, is flat and not itchy or painful in the slightest! I have not used any steroids or anything other than the autoimmune protocol and the 21-Day Sugar Detox to achieve these results.

Why do I think that eating fruit is such a problem for me? There is a strong link between elevated blood sugar and autoimmune disease. Only a few years ago, I was obese and had pre-diabetes among my laundry list of health conditions. I think it’s fairly obvious that before the detox, I was eating enough fruit to cause enough of a spike in my blood sugar (and enough of a release of insulin) to perpetuate some inflammation and continue to stimulate the immune system. I was healing, so clearly I wasn’t causing such a spike in blood sugar to completely derail all of my other efforts–but regulating my blood sugar more tightly has obviously created an environment within my body more conducive to healing. And that is the whole point. Not everyone with autoimmune disease is going to need to go to these lengths to regulate their blood sugars. This is what I need to do likely because of the long lasting damage being obese did to my metabolism.

So, what did I eat in week 3? I didn’t actually post all of my photos on Facebook this week (in part because I was busy and in part because those meals were very similar to several I had already posted). But, I did take photos, and here is the round-up.

# of cups of bone broth: 1
# of meals with bone broth as an ingredient: 3
# of meals that included organ meat: 10 (heart and liver this week)
# of meals that included fish: 5
# of meals that included bacon: 6 (pastured, sugar-free, nitrate/nitrite-free from )
# of meals that included vegetables: 21
# of meals that included meat on the bone: 1
# of meals that included fermented food: 8
# of meals that included seaweed: 0
# of snacks: 0
# of days with a spoon of coconut oil between meals: 0
# of meals shaped like a smiley face: 2

So, where do I go from here? Not backwards, that’s for sure! This is working just too darned well for me! I have adjusted to 1 or 2 servings of fruit per day and my plan is to keep it that way (especially since my sleep and energy levels seem so good!). It is important to me to allow more flexibility in my life. The autoimmune protocol is restrictive enough and I have to be cautious that I don’t create such a sense of deprivation in myself that I rebel and make really, really bad choices. So, what being off the 21-Day Sugar Detox means for me now is simply that those servings of fruit can be any fruit. In fact, my breakfast this morning (which was my first post-detox meal) looked an awful lot like my breakfasts throughout the 21-Day Sugar Detox, except I ate a bowl of blackberries instead of half a grapefruit. And were those blackberries ever the sweetest most wonderful tasting things ever!

Would I do it again? Yes! In a heartbeat! But, WILL I do it again? I hope I don’t need to. I hope that what I’ve learned stays with me and that this is just the way I eat now. If I can accomplish that, then there will be no need to repeat this experiment. Do I recommend the 21-Day Sugar Detox? Just like everything, I don’t think it’s for everyone. If you know you’re a person for whom firm rules creates disordered eating, then this is not for you. If you know that plowing through an adjustment period to get to the rainbow at the other side works for you, then this is a great way to go. I for one, am greatly enjoying the pot of gold (er, blackberries) at the other side.

Tags: 21, 21DSD, autoimmune, carbohydrates, completed, day, detox, diane, difference, disease, dramatic, eat, energy, fatigue, Food, fruit, healing, How To, illness, inflammation, lichen, planus, protocol, round-up, sanfilippo, Sleep, Sugar, summary, what
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My 21-Day Sugar Detox Update: 2 Week Down, 1 To Go!

January 15, 2013 in 2013

So, I have been following my slightly modified version of Diane Sanfilippos’s 21-Day Sugar Detox for TWO whole weeks (my modification is the addition of grapefruit to the list of allowed fruits, which I explain in this post). I have been doing this in conjunction with following the autoimmune protocol, trying not to snack (no snacks this week, woot!), and starting to wean myself off of caffeinated tea. Admittedly, I am still drinking about at least twice as much black tea as I feel I should be–but I find black tea so comforting and when you combine doing the 21-Day Sugar Detox with the late nights and early mornings of this past, it’s so hard to resist!. Improvement needed on the caffeine front, but I’m okay if the transition is gradual.

Last week, I reported that my 21-Day Sugar Detox was going well but that I wasn’t seeing any big differences (see this post).

So, how is it going after week 2? This is actually hard for me to admit. It’s going freakin’ awesome. My skin looks great. My lichen planus lesions seems to be healing more quickly (I’ll post before and after photos with my final update next week). My energy seems better. My brain seems to be working faster and more clearly. My productivity seems higher. My clothes are fitting so much better. I’ve had no bloating whatsoever. Oh yeah, and I lost two pounds!

Wait, so why didn’t I want to admit that the 21-Day Sugar Detox is doing amazing things for me? Because it means that the amount of fruit that I was eating before was a problem, that I wasn’t managing my blood sugar levels optimally and that that was contributing to some inflammation. Dang. But, this was the point of the experiment: to test how important limiting fruit intake is for my body to heal from this autoimmune disease. I guess, it’s more important than I thought. Double dang.

The hardest part of this week was the combination of my daughter’s 6th birthday on Friday (I made paleo cupcakes to bring to her school and for birthday cake after supper that night) followed by a friend’s birthday party on Saturday where they made paleo baked goods (from my recipes!) for us to enjoy! Everything had nuts, eggs, and sugar of some form. And I did not touch even one minute bit of it. But, I did feel deprived. Combine that sense of deprivation with The Great Server Malfunction of 2013 (we’re still knocking on wood here), and I did have to resort to some comfort bacon. But, I did feel empowered and proud of myself for getting through those days and that sense of deprivation did subside.

So, even though there is a full week left to go, I’m now trying to think about what ending the 21-Day Sugar Detox will mean for me. Now that I am feeling like limiting fruit on a regular basis is probably best for me, I think the first step is simply going to be adding back in variety (I really miss berries!). Then, I think I will just keep to 1-2 servings of fruit per day, but maybe not be quite so rigid. I’m also going to let myself lick my fingers if I get maple syrup or honey on them (because that has actually in many ways been the hardest part for for me). I feel like I want to see how far this will take me. And even though I miss fruit and miss eating a whole lot of it, I am always motivated by things that make me feel really good. And the 21-Day Sugar Detox is making me feel great!

Once again, I have been taking photos of my meals and posting them on Facebook to share with anyone who is interested. Many people see the autoimmune protocol as so restrictive that you can’t possibly eat good food, so it’s nice to be able to show evidence to the contrary. It’s also nice to share with you just how often I eat fish, organ meat, broth, and fermented foods, which many people are intimidated by when they first approach the autoimmune protocol. I also want to share with people just how much food (and fat!) you can eat and still lose weight, keeping in mind too that it’s much more challenging to lose weight closer to your goal weight like where I’m at (which is why two whole pounds is a pretty big deal!). I hope that you have found these photos useful and/or inspiring. You’ve probably noticed that I really do like to eat the same thing most mornings for breakfast. Creature of habit that way, I guess.

Here are my meals for week 2 of my 21-Day Sugar Detox while still following the autoimmune protocol.

I shared these photos on Facebook (with a description of what each meal included), but I thought those of you who aren’t as plugged into social media as I am (or for those who find the week in review interesting) might enjoy seeing them here.

I’m not going to re-itemize everything I ate this week (you can go back over my Facebook posts if you’re really interested), but since I’m on the autoimmune protocol, I thought you might be interested in a few super/healing food facts:

# of cups of bone broth: 2
# of meals with bone broth as an ingredient: 7
# of meals that included organ meat: 13!!! (heart and liver this week)
# of meals that included fish: 5
# of meals that included bacon: 1 (pastured, sugar-free, nitrate/nitrite-free from )
# of meals that included vegetables: 21
# of meals that included meat on the bone: 0
# of meals that included fermented food: 13
# of meals that included seaweed: 1
# of snacks: 0
# of days with a spoon of coconut oil between meals: 0
# of meals shaped like a smiley face: 0 (this can not be allowed to continue!)

Tags: 21, 21DSD, AIP, autoimmune, day, detox, disease, eat, energy, healing, How To, images, meals, paleo, protocol, sample, skin, Sugar, two, update, week, weeks, what to
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The Benefits of Intermittent Fasting

June 9, 2012 in Beyond Paleo, Food Issues, Hormone Regulation, Paleo Philosophy, Weight Loss/Gain

Intermittent fasting, or IFing, is a very popular strategy for stimulating healing, increasing longevity, balancing hormones, increasing energy and mental clarity and losing weight. If you’ve heard this term bantered around paleo circles and have been wondering what it’s all about, then wonder no longer!

How does Intermittent Fasting work? Intermittent fasting provides a variety of health benefits, predominantly due to stimulating a process call autophagy. Autophagy is the process by which a starving cell can reallocate nutrients from cell machinery that is not working optimally to fuel more essential cell processes. The cell degrades its own components, including damaged organelles, cell membranes and proteins, in a tightly regulated process. Autophagy can destroy viruses and bacteria within the cell that are resistant to other ways a cell might destroy them. It can even help the cell identify a viral infection that may have otherwise gone undetected. Autophagy plays a crucial role in immunity and inflammation, balancing the beneficial and detrimental effects of immunity and inflammation, and thereby may protect against infectious, autoimmune and inflammatory diseases. It may even prevent cells from becoming cancerous. Autophagy plays a normal part in cell growth, development, and homeostasis, helping to maintain a balance between the synthesis, degradation, and subsequent recycling of cellular products. In fact, failure of autophagy is thought to be one of the main reasons for the accumulation of cell damage and aging. Turning on autophagy is extremely beneficial (whether it’s turned on by intermittent fasting, exercise, ketosis, or straight calorie-restriction). The result is healthier, more efficient cells, which means a healthier, more efficient body.

What are the benefits of Intermittent Fasting? The benefits of intermittent fasting can be inferred from the effects of autophagy. However, more and more scientific studies are being conducted to confirm the effects of Intermittent Fasting and also isolate the optimal strategy for putting it into practice. Many of the benefits listed below have not been directly tested in humans using Intermittent Fasting; however, there is either strong evidence from animal studies or evidence from studies of autophagy itself, combined with anecdotal evidence to support these claims. The benefits of Intermittent Fasting include:

Increasing lifespan.
Increasing insulin sensitivity, which has many health benefits in and of itself. Of interest, the resulting increase in insulin signaling in the brain is thought to be how fasting/calorie restriction works to increase lifespan.
Lowering blood lipids, triglycerides and other markers of metabolic syndrome.
Fighting/preventing cancer. There is also some evidence that fasting before chemotherapy treatments can help reduce the negative side effects.
Increasing growth hormone secretion (which builds muscle and burns fat).
Normalizing expression of the hunger hormone ghrelin, thereby reducing appetite.
Promoting brain and peripheral nervous system health by increasing neuronal plasticity and promoting neurogenesis, which has a large variety of effects such as boosting mood, memory, and mental clarity.
Increasing dopamine production, thereby boosting mood and increasing anticipation and response to rewards (meaning we get more enjoyment from less food).
Increasing energy through regulating metabolic hormones.

Intermittent Fasting is a little like hitting a reset button. It can help curb sugar cravings, restore energy, and even promote deeper sleep.

How do you do it? And how often? There are many options, but in general fasting for at least 16 hours is required to receive any benefits. Fasting beyond 24 hours doesn’t extend those benefits. So consider a fast anywhere between 16 and 24 hours. This includes sleep time, so a great way to intermittently fast is to simply skip breakfast. Ideally, that also means skipping your morning coffee. Drinking water is okay. Expect to feel hungry when you fast. This is different than simply listening to your body’s cues and waiting until you are hungry to eat (although many people are opportunistic about when they fast and simply choose days when they aren’t that hungry anyway). If you want to fast for 24 hours, you can skip breakfast and lunch. In terms of frequency, it is perfectly safe to fast 2 or 3 times per week (in the absence of health conditions that might complicate matters). If you prefer a longer fast, then once or twice per week is fine. Some people opt to have an 8-hour feeding window every day (see Leangains). However, I would argue that a daily fast is no longer intermittent. The body is able to adapt and predict the fast and many of the benefits are dulled. I also want to point out that you can benefit from fasting even if you do it very infrequently. Perhaps you only want to fast once per month, or once every few months. There is no clear evidence that fasting frequently will dramatically improve your health. Try it, see how you feel, see how you feel when you try it the next time, and then decide what is best for you.

What should you break fast with? When you are ready to eat, eat a balanced meal with lots of great protein and tons of veggies. You probably won’t feel very good if you eat too many carbs, so I urge caution with starchy vegetables and fruit. And don’t overdo the quantity you eat; try and aim for a normal meal (or only slightly larger than normal). I actually found in my own experimentation that I wasn’t that hungry and would eat an unusually small meal to break fast (I would then have more appetite for the meal after that).

Is fasting for everyone? The answer to this is a resounding NO! If you are not getting enough sleep or if your stress is not well managed, you may experience exaggeratedly high cortisol production in response to fasting, which can be detrimental. If you have a history of metabolic derangement or adrenal fatigue, I urge caution for the same cortisol-spiking reason. Women may be more likely than men to have an exaggerated cortisol spike in response to fasting (here‘s a great post reviewing women-specific responses to fasting). If you are not currently eating a fairly low carbohydrate diet (say, less than 100g per day), then fasting may have some side effects that mask the benefits (like headaches, fatigue, and nausea, caused by high cortisol). If you have any grains or dairy in your diet, you may experience a withdrawal-like effect because you aren’t consuming the opiate-like substances found in those foods. If fasting does not feel good, then don’t do it. If fasting feels good the first few times, but then stops feeling good, then stop. My own personal experience with intermittent fasting led me to realize that I can only get away with doing a 16-hour fast once or twice per month. Any more frequently and the cortisol spike stops weight loss, wrecks my sleep, and makes the whole experience completely pointless.