This broke my heart, because I am the Queen of eating every few hours. Initially I was really only hungry 3 times a day, but in every magazine I read it said to eat small meals every 3-4 hours. Now I need to eat every few hours or else I feel like I’m starving. But enough about me, let’s talk about how false this is.
This study is my favorite. They took a few obese women and put them on a 1,000 calorie a day diet. Some of the women ate the 1,000 calories in two 500 calorie meals, the other group ate the 1,000 calories split up over the day. What did they find? At the end of 4 weeks the weight loss was the same in the two groups – they lost about the same amount of fat, muscle, etc. They found that the energy expenditure and the diet-induced thermogenesis (what people THINK is an increase in metabolism when you eat multiple times a day) were the same in the two groups. The most interesting part of the study, however, was that after 4 weeks the “nibbling” group had a decrease in sleeping metabolic rate. So the group that ate twice a day had a higher metabolism at night while asleep than the nibbling/grazing group. This study found the exact same thing.
This study takes it a bit further. They looked at it from a weight loss and satiety perspective. Shouldn’t the people who ate multiple times a day be less hungry, and therefore have less Ghrelin, the hormone that stimulates appetite? PYY, the other hormone, does the opposite – it tells you your full. Shouldn’t people who “graze” or “nibble” have more PYY and less Ghrelin during the day? Nope. Both people who ate 3 meals a day and those who ate 3 meals + 3 snacks had the same levels of both hormones. Well, there goes that.
Kinda on the same vein another study looked at how eating 2 meals a day and eating 3 meals a day affected weight loss. Eating 3 meals a day showed an increase in 24h fat oxidation over the 2 meals, but had a lower fat oxidation at breakfast (fat oxidation = breaking down fats in the body into smaller pieces to use for energy). Not surprisingly they found that the people reported feeling more satiated over 24hours with 3 meals a day than 2. However, this differed from the previous study which measured levels of the hormones responsible for these feelings. In this study, they asked the subjects, meaning this finding may be just based on people being used to eating multiple times a day, or the thought of not eating, etc. If you read the conclusion of the study they get all sciencey and brainy on it, I’ll let you make your own decisions.
This study may be where this information of 3-4 hours comes from. It shows that people who nibble/graze have the same level of carbohydrate and fat oxidation during the day. There is no “spike” in metabolism or carb or fat oxidation, it’s pretty much the same all day. People who eat 2/3x a day have peaks, which are compensatory. For example, carbohydrate oxidation is increased after first meal (hearing “breakfast is the most important meal” anyone?) and was decreased over the fasting period (last meal of the night to first meal in the morning). HOWEVER: during the time your carbohydrate oxidation is low, your fat oxidation is HIGH to compensate for energy. So while breakfast proponents tout that your carbohydrate oxidation is low and you need to boost it, they kind of ignore that your fat oxidation is high to compensate. Your body is a well oiled machine guys!
Moral of this story? As long as you eat in a deficit, it doesn’t matter how many times a day you eat. Your metabolism doesn’t “boost” when you eat multiple times a day. Your BMR is your BMR whether you eat 100 calories every 2 hours or a few 500 calorie meals a day. My take? Eat when you’re hungry. It’s a crazy concept, but do it.