A quick google search will yield hundreds of resources telling you that the healthiest way to eat is to graze, to eat small quantities nearly constantly throughout the day. When I had gestational diabetes with my first daughter, I was told never to let more than 3 hours pass between meals or snacks. Like so many people, this dogma was completely ingrained in my psyche (at least until researching a paleo diet challenged me to reevaluate everything I thought I knew about nutrition). I remember going on a complete rant with my poor baby brother about the importance of eating more frequently during the day and of never skipping breakfast. How embarrassing to find out later that my brother’s natural tendency to eat just one big meal a day is actually healthier for him than the 6 small meals a day that I was trying to talk him into.
Like so many of the current dietary recommendations made by doctors, nutritionists and the FDA (like eating low-fat or eating whole grains), the idea that eating frequent small meals is better for you is based on bad science and assumptions. The science which supports increased eating frequency is based on correlative studies (basically surveys), which have shown that the more frequently a person eats, the more likely that person is to be a healthy weight. However, this correlation disappears completely once exercise is accounted for (a fact that is often ignored when the case is being made for more frequent meals). Prospective studies (where people are put on specific diets and then monitored for health and weight changes) have universally shown that increasing eating frequency results in no benefit in normal weight individuals and results in a tendency toward weight gain and higher risk of diabetes in already overweight people.
Analysis of Hunter-Gatherer populations (modern and historically studied) shows that these populations typically eat one large meal in the afternoon or evening. A small meal of leftovers is sometimes ingested in the mornings as are small amounts of food as it is gathered (information Dr. Loren Cordain’s blog www.thepaleodiet.com and from The Paleo Answer). Not only does this not look anything like the 5-6 small meals a day that are advocated for optimal metabolism, but it doesn’t even look like the 3 “square” meals that increased eating frequency is compared against! When we start to consider eating one meal per day (without restricting calories), there are some interesting research findings. One study showed that eating one meal per day in the absence of calorie restriction improves body composition, cardiovascular risk factors and reduces cortisol1. Another study showed that eating one meal per day reduces inflammation by blunting the ability of circulating white blood cells (specifically monocytes) to produce cytokines (chemical messengers of inflammation)2. There is also speculation that decreased meal frequency would result in decreased oxidative stress and increased leptin and insulin sensitivity. However, another study shows lower glucose tolerance by eating one meal per day3 (although this is not a bad thing in the context of a lower carbohydrate diet). Although compelling, these studies are not sufficient to make a case for one meal per day. The fact is that this field is so under researched that a strong case for any meal frequency simply can not be made.
So, how often should you eat? I think the most important thing that you can do is to listen to your body. Eat when you are hungry and eat until you are full. I think the far bigger contributor to your health is what you choose to eat and not when or how often you choose to eat it. Although, I will also throw out the caveat that if you are substantially overweight or have elevated cortisol levels (due to adrenal fatigue or unmanaged stress), your hunger hormones are likely disregulated. In that case, in addition to eating lower carbohydrate and concentrating on food quality, it’s important to try and space your meals (maybe 2-3 meals per day and maybe 1 snack) in an attempt to restore your hunger signals to trustworthy levels. So, Bro–I’m so sorry! I was wrong. Listen to your body. If you aren’t hungry until the evening, then don’t eat until then!
1Stote et al. “A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults”. Am J Clin Nutr; 2007, 85:981-988
2Dixit et al. “Controlled meal frequency without caloric restriction alters peripheral blood mononuclear cell cytokine production” Journal of Inflammation, 2011, 8:6
3Carlson et al. “Impact of Reduced Meal Frequency Without Caloric Restriction on Glucose Regulation in Healthy, Normal Weight Middle-Aged Men and Women” Metabolism. 2007; 56(12): 1729–1734.