Proponents of grazing claim that frequent, small meals rein in your appetite and keep you from eating indiscriminately when it's finally mealtime. Whole diet schemes are based on the timing and frequency of meals, some even going as far as promising that stubborn belly fat will melt away if you just spread what you usually eat into frequent small portions.
So how important is meal size? How important is timing? Despite what diet plans claim, the science is scant and with conflicting results.
The appetite argument
A new study led by Martine Perrigue in the American Journal of Clinical Nutrition addresses the appetite control issue. It's a small experimental trial, with 12 volunteers, who were fed the same amount of food daily, in either three larger meals or eight smaller ones, each participant on both eating frequencies for three weeks at a time. Their appetite was assessed every 30 minutes by rating hunger, desire to eat, fullness and thirst on the last day of each experiment.
Smaller meals didn't seem to control appetite in this study, and when the same amounts of calories were consumed there was no difference between the two conditions.
The authors relate their findings to those of other experimental studies, but that's a difficult task: One study compared one big dinner as the sole daily meal to three meals a day, with appetite assessed right before dinner -- it's hardly a surprise that the 1-meal-a-day condition resulted in a big appetite reported before dinner. In another study, obese men were fed either one breakfast, or the same amount of calories divided into five hourly meals; at lunchtime they reported less hunger with the higher eating frequency. So testing conditions and results vary, and the authors conclude that:
"Taken together, the published studies to date suggest that the relation between EF (eating frequency) and appetite is complex and will require further study before definitive recommendations can be offered to the public."
Revving up metabolism
The other claim the small-and-frequent proponents make is that this eating style boosts metabolism and burns more calories, and that wide intervals between meals, on the other hand, cause stress and storage of fat because the body fears famine is upon it.
This sounds plausible, and quite colorful, but is there good proof of that?
There are numerous studies trying to address this issue, and when those are taken together in review there's little evidence that high meal frequency boosts metabolism.
And lets also remember that three meals a day is hardly infrequent. Humans have thrived on just one meala day for a very long time -- not that I wish that on anybody.
Bottom line: Eating frequency is more habit that physiology. Beyond disease states and extreme situations it seems that most healthy people can do well when the food they need is spread in many different ways. What matters is what and how much you eat.
There are of course individual preferences. I'm a grazer. I can't wait for my next apple break, and don't really enjoy big meals. It's all about joy of food though, not about weight control.
So as the holiday season approaches, think about it: you can eat little and often, or a big meal infrequently, but you can't do both without consequence.
Dr. Ayala