By far one of the most common tips you’ll come across when looking for weight loss advice is that small, frequent meals are an effective strategy for speeding up your metabolism. In fact most sources would have you believe that as far as nutrition goes for fat loss, the top key points are to eat clean, manage your calories and carbs, and eat small, frequent meals.
Recent research, however, has revealed some interesting facts about this common practice that may come as a surprise to many. What has been discovered is that although there are certainly benefits to eating small, frequent meals for fat loss, the picture is actually quite different to what’s generally believed to be true.
So how is meal frequency supposed to affect your metabolism, anyhow?
Every food you eat requires your body to expend some amount of energy to process it as part of the digestive mechanism. In other words, it stimulates your metabolism to burn some calories. This is referred to as the Thermic Effect of Food. Some foods have a greater thermic effect than others.
The logic behind the commonly-held small, frequent meals argument is that by eating regularly, every two-and-a-half to three hours or so, you keep your metabolism active because your body is constantly working away processing food in digestion.
Even though the actual number of calories burned by your body processing the food you consume during the day may be the same, your digestive system spends less time doing nothing, so to speak. So that means your metabolism spends more time in a stimulated state, causing it to adapt by speeding up, essentially.
So much for the theory . . .
How much of an effect does eating small, frequent meals actually have on your metabolism?
According to the research . . . none!
One study conducted in 2010 by the University of Ottawa, for example, looked at two groups of obese subjects following a restricted-calorie diet over an 8-week period. Both groups had exactly the same calorie intake each day, although one group had 3 meals per day, while the other had 3 meals plus 3 snacks.
The study found that both groups experienced decreases in body weight, fat mass and BMI, however there was no significant difference in the amount of weight loss and fat loss between the two groups. It therefore concluded that under the conditions they tested, increasing meal frequency doesn’t promote greater weight loss.
A detailed review of possible explanations behind a metabolic advantage of increased meal frequency or regular snacking meal failed to find any significant benefits in terms of energy expenditure.
Numerous other studies also support these findings. In fact, the bulk of recent research indicates that increasing meal frequency actually doesn’t increase diet-induced thermogenesis (the amount of energy burned in processing your food) or your metabolic rate at all.
Are there any benefits to eating small, frequent meals?
There’s a lot of anecdotal evidence out there that eating small, frequent meals does in fact help individuals to lose body fat. But science tells us that it’s not because of an effect on energy expenditure or metabolism. In fact, studies assessing total 24-hour energy expenditure find no difference between nibbling and gorging.
What exactly is behind the benefits that people are supposedly experiencing, in that case?
Interestingly, there are in fact several real benefits for fat loss, as well as health, to eating small, frequent meals. Ironically however, none of these involve increased metabolic rate, which is the reason behind most people believing in meal frequency.
The first benefit is connected with the effect it has on your food intake. Eating smaller meals helps you to manage your food intake by helping you to feel satisfied more quickly.
People who are accustomed to having fewer, larger meals generally need to eat larger meals for their stomach to feel full and to feel satisfied with their meal. In addition, the longer the duration between meals, the greater your level of hunger at each meal time, and therefore the greater your chance of overeating to psychologically suppress that hunger.
By eating small, frequent meals on the other hand, you become accustomed to being satisfied very quickly, in fact in many cases just a small snack will satisfy your hunger quite effectively.
A 2005 study by Georgia State University, for example, found that athletes who were given 250-calorie snacks three times a day between meals actually self-regulated their regular meals by eating less at those meal times because of the satiating effect of the snacks.
Increasing meal frequency has also been shown to have several health benefits. It has been found to have positive effects on LDL (bad) cholesterol level, total cholesterol level, and insulin level.
Insulin level is associated with your blood glucose level, as well as a dangerous condition known as Metabolic Syndrome.
Whenever you consume food, the energy from the carbohydrates enters into your bloodstream as blood glucose (also known as blood sugar). The degree and duration of the resulting rise in your blood glucose level depends on both the type of carbohydrate you consume and also the quantity.
When your body senses a rise in your blood glucose level, it secretes insulin into your bloodstream to transport the glucose into your cells and liver. The greater the blood glucose rise, the greater the insulin response.
Consistent large rises and falls in your blood sugar level over time are a bad thing. They lead to Metabolic Syndrome, which has been associated with a number of serious conditions such as heart disease, stroke and cancer. As part of Metabolic Syndrome, the cells of your body also become resistant to the action of insulin, so your body is therefore forced to secrete even higher levels to do the same job.
Regularly high insulin levels are also bad since high insulin levels act to inhibit fat burning and also promote fat storage.
Having small, frequent meals leads to a more stable blood glucose profile since the rise in your blood glucose level is naturally smaller for a smaller meal.
In addition, having some undigested or partially-digested food in your digestive tract during a meal also tends to reduce the GI (Glycemic Index) of any carbohydrates you consume. This means that the energy from the carbohydrates transfer into your bloodstream more slowly, resulting in a less pronounced blood glucose rise. This condition is naturally far more likely with small, frequent meals each day than with a few larger daily meals.
This isn’t to say however that eating three normal meals a day leads to poor blood glucose and insulin control, and subsequently Metabolic Syndrome. It simply means that higher meal frequencies seem to reduce the chance of these issues occurring by improving blood glucose and insulin control. This is particularly important for people who have high-carbohydrate diets or who follow the unhealthy practice of frequently eating carbohydrates on their own.
Lean body mass
A study conducted in Japan in 1996 involving 12 boxers looked at the effects of meal frequency on lean body mass while dieting. The study compared two groups, both consuming 1,200 calories a day for 2 weeks, one having 2 meals a day and the other having 6 meals a day.
The study found that the decrease in lean body mass was significantly greater in the 2-meal group than in the 6-meal group, and therefore concluded that lower meal frequency leads to a greater protein catabolism (breakdown), even if the same diet is consumed.
This suggests therefore that increased meal frequency is beneficial for maintaining lean body mass while dieting.
What the International Society of Sports Nutrition says:
The following excerpt defines the position of the International Society of Sports Nutrition on meal frequency:
Admittedly, research to date examining the physiological effects of meal frequency in humans is somewhat limited. More specifically, data that has specifically examined the impact of meal frequency on body composition, training adaptations, and performance in physically active individuals and athletes is scant. Until more research is available in the physically active and athletic populations, definitive conclusions cannot be made. However, within the confines of the current scientific literature, we assert that:
- Increasing meal frequency does not appear to favorably change body composition in sedentary populations.
- If protein levels are adequate, increasing meal frequency during periods of hypoenergetic dieting may preserve lean body mass in athletic populations.
- Increased meal frequency appears to have a positive effect on various blood markers of health, particularly LDL cholesterol, total cholesterol, and insulin.
- Increased meal frequency does not appear to significantly enhance diet induced thermogenesis, total energy expenditure or resting metabolic rate.
- Increasing meal frequency appears to help decrease hunger and improve appetite control.
Are there any disadvantages to eating small, frequent meals?
An important part of any fitness or weight loss program is resistance training for muscle growth. This is for two reasons.
Firstly, some level of muscle growth is necessary for the development of a nice, aesthetically pleasing physique. This is the case even if your goal is to simply “look good” without necessarily looking like a fitness model.
And secondly, muscle tissue is a key component of your body’s metabolic rate and is therefore an important contributor to fat loss. This is why gaining muscle tissue helps fat loss, and why losing muscle tissue hinders fat loss.
Recent and ongoing studies by leading researchers such as Dr. Layne Norton and Professor Stuart Phillips have shown that meal frequency has a significant effect on muscle protein synthesis (MPS), or the process of converting dietary protein into muscle tissue.
It’s been shown that significant MPS is triggered in your body only in the presence of a threshold amount of protein, which varies according to body weight, age, and various other factors. If less than the threshold amount of protein is present in a meal, it won’t trigger a significant MPS response.
What this means is that consuming frequent, small amounts of protein throughout the day is actually not conducive to muscle growth. Having too many daily meals will lead to a situation where each meal doesn’t contain sufficient protein to trigger much MPS and therefore your muscle growth will be impaired.
How many daily meals are optimal?
Having small, frequent meals is beneficial therefore, but only to the point where it doesn’t lead to an excessively low protein content in each meal. At that point it becomes too many meals.
At the other end of the scale, having too few meals is also problematic, for two reasons. Firstly, the fewer daily meals you have, or more specifically, the fewer protein doses you have, the fewer MPS response “events” you subject your body to, to feed muscle growth.
And secondly, as was shown in the 1996 Japanese study mentioned earlier, having too few meals while on a calorie-restricted diet can lead to catabolism (muscle wasting) as your body turns to muscle tissue for its protein and energy requirements during extended fasting periods.
The optimal number of daily meals for each individual is best determined by trial and error since there are a number of influencing factors, including body weight, body composition, age, the type of exercise program, the person’s goals, and so on.
In my opinion a good starting point for most people would be five meals per day, after which you could test four meals, followed by six. I don’t believe that more than six daily meals would be beneficial in most cases, however.
- Cameron JD, Cyr MJ, Doucet E. “Increased meal frequency does not promote greater weight loss in subjects who were prescribed an 8-week equi-energetic energy-restricted diet.” The British Journal of Nutrition, 2010.
- Bellisle F, McDevitt R, Prentice AM. “Meal frequency and energy balance.” The British Journal of Nutrition, 1997.
- Benardot D, Martin DE, Thompson WR, Roman S. “Between-meal energy intake effects on body composition, performance and total caloric consumption in athletes.” Medicine and Science in Sports and Exercise,
- La Bounty PM, Campbell BI, Wilson J, Galvan E, Berardi J, Kleiner SM, Kreider RB, Stout JR, Ziegenfuss T, Spano M, Smith A, Antonio J. “International Society of Sports Nutrition position stand: meal frequency.” Journal of International Society of Sports Nutrition, 2011.
- Iwao S, Mori K, Sato Y. “Effects of meal frequency on body composition during weight control in boxers.” Scandinavian Journal of Medicine & Science in Sports, 1996.