Small, frequent meals vs. 3 squares a day

I have just discovered a new trove of blog topic material: the students in the nutrition class that I TA. The class's instructor requested that the TA's collect a nutrition-related question for each student, to help guide her lectures. But I think that a lot of their questions are probably the same questions that a lot of people have. But most people don't ever take a college nutrition course to learn the answers. So, I've decided to try to answer some of their questions (and maybe yours, too).

First up: Is it better to eat 3 meals per day or more frequent, smaller meals?

When I was an undergrad what feels like millenia ago, I thought I knew the answer to this. My then-boyfriend and now-husband used to think that the anonymous posters on internet bodybuilding forums were the best source of information about this kind of thing. And according to BigGuns123 and SwoleDude456, it was a no-brainer: 6 small meals per day was best for gaining muscle and losing fat. Period.

WARNING: Science-y stuff ahead. Skip this section if you are easily bored
Their argument was that after 3 hours of not eating, the body would start to break down muscle (they even used the word "catabolize" so they'd sound smarter), which ultimately leads to a decrease in metabolism. Also, the process of digestion itself was supposed to boost metabolism. I have some serious doubts about these theories. It is true that some calories are burned during digestion, but I don't see any reason to believe that the body would burn more calories digesting 300 calories 5 times than it would digesting 500 calories 3 times. The energy that is used during the breakdown of nutrients is the result of the way the chemical bonds in those nutrients are broken. So, the amount of energy needed for digestion during any given day should be dependent on the amount and type of nutrients consumed, not how often they are consumed. Second, although I am not an expert on metabolism, I am pretty confident that muscle breakdown does not occur to a great extent until fasting has been prolonged. Instead, during at least the initial 4 hours after a meal (1), the body's stores of glucose (glycogen) are used for energy along with fatty acids (from, you guessed it.. fat). Even when muscle is broken down for energy, this would only result in a net loss of muscle if protein intake throughout the day was not sufficient to replace it.

The other, more logical, argument for small frequent meals is this: if you eat regularly, you will not get a chance to feel very hungry. And when you're not ravenous, it's much easier to make smart choices about what you're going to eat and to stop eating when you are full. On the other hand, when you come to the table starving, you will eat whatever you can get your hands on and you will eat much more than your body actually needs.

Regardless of the bases for these theories, they are still just theories. What's important is what actually happens. What evidence is there to support them? As it turns out, this question does not have an easy answer. One study found that children who eat more meals are less likely to be overweight.(2) Eating just one meal per day appears to have negative effects on cholesterol and blood glucose.(3,4,5)However, there doesn't appear to be much research comparing 3 meals per day to 5 or 6 meals per day. So, it is difficult to determine whether one pattern is better than the other.

Here's my stance: Don't eat by the clock. Eat when you are hungry but not starving, and stop eating when you are comfortably full. If you feel hungry 3 times per day, then eat 3 meals. If you feel hungry 6 times per day, eat 6 meals. As always, the total calories you consume matter much more than when or how you consume them. So, eat in a way that will help you to not eat too many calories. If you are prone to snacking mindlessly all day, you may be better off limiting your eating to 3 main meals only. However, if you are more likely to stuff yourself silly at every meal, you may benefit from having smaller, more frequent meals that keep you satisfied all day so you are not driven to overeat.

References
1. Morton, The Digestive System, 2001
2. Toschke AM, Küchenhoff H, Koletzko B, von Kries R. Obes Res. Meal frequency and childhood obesity. 2005 Nov;13(11):1932-8.
3. Stote KS, Baer DJ, Spears K,et al. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. Am J Clin Nutr. 2007 Apr;85(4):981-8.
4. Bhutani S, Varady KA. Nibbling versus feasting: which meal pattern is better for heart disease prevention? Nutr Rev. 2009 Oct;67(10):591-8.
5. Carlson O, Martin B, Stote KS, et al. Impact of reduced meal frequency without caloric restriction on glucose regulation in healthy, normal-weight middle-aged men and women. Metabolism. 2007 Dec;56(12):1729-34.