Will greater meal frequency burn more calories? Will snacking help curb hunger between meals, or stir it up?
A few weeks ago I shared 20 “real” lunches from moms and dads. One recurring theme I heard from parents is the snacking habit, especially from parents working at home during the day. Instead of sitting down for larger breakfasts and lunches, they tended to quickly eat several smaller meals during the day.
Reading this common refrain sparked my curiosity. Does eating more meals really boost our metabolism?
And Science Says…
The research surprised me!
Here’s what I learned after reading the nutrition literature on meal frequency:
1. Eating more frequently shows no greater benefit to metabolism or burning more calories.
2. Snacking does not lead to fewer hunger pangs when compared to 3 meals a day.
3. Eating the majority of daily calories earlier in the day seems to offer many health benefits, such as better fat metabolism, more weight loss, better insulin sensitivity, and improved gut bacteria.
Reading this research on metabolism has already made an impact on my eating habits. Having an understanding of how hunger signals work fundamentally changed how I approach meal planning.
I’ll explore the first two findings in today’s post, and save the third for a future article.
Meal Frequency and Metabolism
So why do we share this belief that more meals means boosting metabolism? Beyond the intuitive appeal, there were a number of studies, primarily in the 1960s and 70s, that concluded more meals burns more calories. It’s the assertions of these studies, shared through fitness and health magazines, that came to settle in our brains as fact.
Reviewing Old Studies
Recent analyses of these studies, however, reveal critical flaws, such as not controlling for physical activity and the unreliability of food diaries. When studies are compared that control for calorie intake and physical activity, the results predominantly show no metabolic differences between 4-6 meals a day versus 3 meals a day.
Here’s an example of a well controlled, randomized study that was published in 2010 in the British Journal of Metabolism. Sixteen subjects were randomly assigned to a 6 meal a day or 3 meal a day regimen for 8 weeks with the same calories and content. Both groups lost weight over the 8 weeks, but there were no differences between groups for body fat, weight loss, hunger hormones, and fullness levels.
Even more convincing is a 2015 meta-analysis of 25 studies that met strict research criteria for inclusion. (Most importantly to control food intake.) Based on the results from these studies, the authors conclude that there is no evidence to indicate a difference in weight loss or calories burned between higher and lower frequency eating. This especially applies when comparing 4-6 meals to 3 meal groups.
Offering scientific consensus on this issue, the 2010 dietary guidelines committee noted that there was “insufficient evidence to recommend increased meal frequency for weight management.“
All of this research has convinced me that the idea of more meals boosting metabolism is a myth. But the next question was the one I really wanted answered…
Doesn’t Snacking Keep Hunger at Bay?
I’ve long assumed that snacking could keep my hunger at bay so I wouldn’t overeat at my next meal. I used to snack around 10AM in the hopes of removing hunger pangs until lunch. The problems arose when I snacked a little too much and then wanted to push lunch later. There went my good eating schedule!
No Differences in Hunger Between Snackers and Non-Snackers
Contrary to common wisdom, the 3 meal a day subjects reported the same levels of hunger as the 4-6 meal a day subjects (results from the same research reviews mentioned above).
In addition to all the reviews mentioned previously, there was a separate 2011 review of studies that looked specifically at the effect of meal frequency on appetite and food intake. The researchers concluded:
“Based on these studies, the claims in the mainstream media of reduced hunger and improved glucose and insulin control with increased eating frequency are unsubstantiated.”
This didn’t make sense to me at first. I thought that nibbling in between meals would dampen hunger pangs and lead to less calories at the next meal.
Understanding ghrelin is what unlocked the mystery for me. Ghrelin is the “hunger hormone” released by the stomach. It’s one of the hormones that makes you get up from your desk and go scrounging in your pantry. But ghrelin tells your brain, “EAT,” not just when you’re in need of calories, but also kicks in based on meal habits.
If you eat 6 meals a day, your ghrelin will fire 6 times a day, giving you hunger cues at those 6 times. However, if you consistently eat only 3 times a day, your hunger signals will fire only at those 3 times (assuming sufficient daily calorie intake).
If you eat at irregular times, your ghrelin will not have any of this “training,” and will fire away at irregular intervals, despite your actual calorie needs at that time.
I’ve been putting this information to work for me. I love the ritual of 3 full meals per day with no snacks. But I was worried about the distraction of hunger pangs between meals until I read about how hunger hormones work.
When I used to experience hunger signals mid-morning, I thought I should quench that hunger so I wouldn’t be ravenous at lunch. However, after learning how hunger signals are cued by regular eating schedules, I tried adding more calories to breakfast and just waiting it out until lunch. It took me about 2 weeks, but the 10AM munchies finally stopped! During those 2 weeks, I just kept telling myself that the hunger wasn’t “real”, it was just a habit. I was able to make it through my hunger pangs until my ghrelin system “learned” my new eating regimen.
It’s such a liberation to be free of snacking and those morning munchies! When I decreased meal frequency to 3 set times per day, my productivity improved because I’m no longer distracted by my stomach. I try to only eat 3 times a day with most of my calories consumed at breakfast and lunch. It takes some effort to ensure enough calories in my early meals, but it’s worth it. Larger meals are more satisfying to me, so I’m happy to have broken the snacking habit!
Based on current evidence there is no difference between 3 meals a day versus 4-6 meals per day in terms of burning calories or experiencing hunger signals.
This seems like good news. It looks like you should embrace whatever meal schedule works best for you, since there is no apparent metabolic advantage of one meal frequency over another. Although I love the 3 meal a day structure, many families struggle with getting enough calories in their breakfasts and lunches to make this schedule work. Snacking is a natural solution. But extra eating episodes come with extra precautions.
It’s important to remember that these studies comparing higher or lower meal frequencies used a specific number of healthy calories and split them evenly through the day. In real life, you get to choose your meal and snacking calories. While healthy snacking is a good choice for hectic schedules, there are risks attached to this eating pattern.
Snacking and Appetite Control
Ideally, snacking should curb appetite so you eat less at main meals. But there is some evidence that snackers don’t eat less at their main meals. When you look at eating trends over the past 30 years, you see that total calories in U.S. adults has gone up , but all those extra calories are in the form of snacks.
And research has shown that most snacks that people eat are less healthy than food eaten at main meals. Snacks, especially those on-the-go snacks tend to be saltier, fattier, more sugary than foods we eat at our main meals.
And unless you are eating a high fiber, low calorie snack, nighttime snacking can be particularly unhealthy. When nightfall comes your body becomes more insulin resistant. This means you’ll have higher circulating blood sugar after eating which leads to greater fat storage.
On the other hand, healthy snacks can add more nutrients for those with busy schedules who don’t have time for larger early meals. As the research shows, in a controlled environment with healthy calories, there is no difference in weight control between 3 and 4-6 meals per day. High fiber and lean protein snacks are best for weight control.
Making Your Hormones Work for You
Whether you eat 3 meals or 6 doesn’t seem to matter in terms of burning calories. When you train your hunger signals to fire along with a regular eating pattern, you remove unwanted cravings that can lead to impulsive eating. The key is finding an eating schedule that can work for you, and stay consistent in your timing day to day. Plan, Plan, Plan your healthy snacks to minimize the pitfalls of frequent meals.