Will Eating 6 Times a Day Rev Up Your Metabolism?
By KAMAL PATEL
Every few weeks, I stay up way too late and catch an infomercial touting the benefits of eating several small meals a day to "stoke the body's metabolic fire." It's often accompanied by some graph involving blood sugar and insulin. Seems like an easy sell — you don't have to starve yourself and you're actually being encouraged to snack!
But a company that sells pre-portioned meals and supplements won't give you both sides of the meal-frequency story. Let's dig in and see exactly what the studies show.
Correlation Is Not Causation
Some studies simply look back on how frequently people ate and record their body weight and fat level. These studies are not the most telling, since how much you weigh isn't necessarily due to eating frequency.
In fact, these studies can be quite misleading. People who eat frequently often eat breakfast every day, and people who eat breakfast tend to exercise more and watch their diets and have other healthy habits. People who eat less frequently are more likely to have chronic conditions such as depression, which can lead to both reduced eating frequency and weight gain.
So any of the dozens of factors that can affect both body weight and tendency to eat frequently could be responsible for the pattern of lighter people eating more frequently. There's also conflicting evidence on the correlation between body weight and eating frequency.
While some studies show a link between eating more and weighing less, others suggest that eating more frequently is correlated with weighing more." So let's just call a spade a spade: These studies should not influence how frequently you eat. Correlation is not causation.
Trials Show No Difference
A more informative type of study is the randomized controlled trial, in which study participants are assigned frequent eating or less frequent eating and then weight is measured. This way you know that the weight change was due to the eating frequency — or are at least a bit more sure.
Unfortunately, trials tend to test the extremes: one meal a day versus five, or three meals a day versus … 14! Which is actually a bit like grazing throughout the day, which some people do. Regardless of how many exact meals are tested, these studies show no difference in body weight, and some suggest that eating fewer meals may actually improve blood sugar and appetite control.
The Elusive "Metabolic Fire"
Aside from these two types of studies, there are also basic science studies that look at how the body works. Is "stoking the metabolic fire" a real thing? In summary, no. You are not a fireplace, and there is no fire inside you.
Simply put, you don't need frequent meals to efficiently turn food or your body's energy stores (fat, carbs or protein) into energy.
If eating less than six meals a day made you burn too much muscle for energy or made fuel burning inefficient, then humans living hundreds or thousands of years ago would have had a tough time surviving: They would have needed to be able to keep a consistent metabolic rate to live and work, even if there were periods of low food availability accompanied by less frequent meals. Current lab studies back this up, showing that meal frequency does not alter metabolism significantly one way or the other.
If eating frequently throughout the day hasn't helped your weight battle, you might consider trying intermittent fasting, which basically means eating within a shorter window of time each day (for example, from noon to 8 p.m. or 10 a.m. to 6 p.m.) and not eating outside of that timeframe.
Intermittent fasting isn't for everyone, but it shows promise for both weight loss and prevention of some chronic diseases.
While eating more or less frequently may help you lose weight, how other people respond is highly individual and hard to predict. To some, many small meals may prevent them from overeating at any one meal, while for others it may increase the risk of binging.
Memorize the term "isocaloric." In trials, as long as study participants get the same amount of calories per day (isocaloric means the same number of calories), they will lose the same amount of weight, whether they eat three, six or nine meals a day.
Remember that correlation doesn't mean causation. Just because your friend is thin and eats six meals a day doesn't mean that eating six meals a day is why your friend is thin. No single strategy is a home run for all people, and eating frequently to stoke the (nonexistent) metabolic fire should be near the bottom of your strategy list.
Readers -- How many meals do you eat during the day? Have you ever tried eating smaller meals more often rather than three meals a day? If so, what were your results? Have you ever tried intermittent fasting? Leave a comment below and let us know.
Kamal Patel is the director of Examine.com. He's a nutrition researcher with an M.P.H. and M.B.A. from Johns Hopkins University and is on hiatus from a Ph.D. in nutrition in which he researched the link between diet and chronic pain. He has published peer-reviewed articles on vitamin D and calcium as well as a variety of clinical research topics. Kamal has also been involved in research on fructose and liver health, mindfulness meditation and nutrition in low-income areas.