One of the most popular advice given as a reply to the question “how do I lost weight quickly”, is to recommend multiple small meals a day. This theory is extremely popular especially because of the recommendation of several celebrity dieticians who swear by this method. Let us look at the real science behind this theory
Aspect of satiety/satisfaction
First the fundamental issue with the “6 meals a day” diet of several celebrity dieticians – what most people miss out is that actually overall calories are dropped in these kinds of diets. The 6 meals a day does not increase amount of food, but actually tries to fool the body into being satiated with less…. by eating more frequently.
The following is the official “position statement” of the International Society of Sports Nutrition
Position Statement: 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:
1. Increasing meal frequency does not appear to favorably change body composition in sedentary populations.
2. If protein levels are adequate, increasing meal frequency during periods of hypoenergetic dieting may preserve lean body mass in athletic populations.
3. Increased meal frequency appears to have a positive effect on various blood markers of health, particularly LDL cholesterol, total cholesterol, and insulin.
4. Increased meal frequency does not appear to significantly enhance diet induced thermogenesis, total energy expenditure or resting metabolic rate.
5. Increasing meal frequency appears to help decrease hunger and improve appetite control.
There are various studies around this aspect – and several of them disagree on the satiety of high meal frequency vs low meal frequency. However, all of them agree that meal frequency does not help in metabolism or body composition.
Correlation is not causation
There are a lot of studies that show that because two things are related, they are caused by each other. For example,
A lower eating frequency predicts a greater gain in adiposity in adolescent females. Intervention trials are needed to test if changing the frequency of eating can affect obesity risk.
These are some of the studies most often quoted to prove that frequency of eating has a reasonable correlation with obesity. Obviously, they are correlated, but could happen for a variety of different reasons – for example, the subjects need to be double checked for smoking (which reduces appetite) and several other factors that could have been indirectly causing obesity.
What about impact of meal frequency on other metabolic markers (blood lipid level, cholesterol level, etc.)
The higher rise and subsequently fall of insulin in the LowFrequency diet did not lead to a higher fat oxidation as hypothesized. The LowFrequency diet decreased glucose levels throughout the day (AUC) indicating glycemic improvements. RestingMetabolicRate and appetite control increased in the LowFrequency diet, which can be relevant for body weight control on the long term.
Eating only breakfast and lunch reduced body weight, HFC, fasting plasma glucose, C-peptide and glucagon, and increased OGIS, more than the same caloric restriction split into six meals. These results suggest that, for type 2 diabetic patients on a hypoenergetic diet, eating larger breakfasts and lunches may be more beneficial than six smaller meals during the day.
The 6 isocaloric meal pattern led to a reduction in BMI, lipid profiles (total cholesterol, LDL-C, triglyceride), and leptin concentrations and an increase in HDL and adiponectin compared to the normal diet.
What the hell ? None of these studies seem to agree with each other – all of them have fairly conflicting results. So what do I believe in ?
This is precisely the problem I wanted to illustrate – just increasing meal frequency and eating more will actually cause more trouble… while changing meal frequency while eating the same has no predictability, because it depends on so many other factors (your particular diet, age, diabetes condition, etc.)
So what works ? Exercise and simultaneously reducing your calories.
My belief – the pancreatic theory
Warning: this is what I personally believe in. As I listed above, the published research has not come to a settling conclusion.
There are two phases for insulin secretion. The first phase lasts for approximately 10 minutes: in this, phase 1 this stored insulin is released. In phase 2 the pancreas produces more insulin. Eating every 2-3 hours puts a strain on the pancreas because it is unable to produce the stored insulin for phase 1. In fact, problems in Phase 1 is an independent predictor of type 2 diabetes .
One of the reasons is this : As we eat, leptin levels should rise, increasing satiety as well as communicating with the pancreatic cells to stop producing insulin. On the other hand, an increase in insulin increases leptin. If we continually secrete insulin, increasing leptin, we could be at risk for leptin + insulin resistance and metabolic syndrome.
At the same time, Glucagon communicates with the liver to release its stored glucose to maintain blood sugar levels. Insulin and glucagon cannot be present in the bloodstream at the same time, so this occurs roughly 3 hours after eating a meal. Glucagon triggers fat burning – If we consume a meal every 2-3 hours glucagon is never released (because insulin is continually released) and we never enter this fat burning period. This is why I prefer a fasting based diet (alternate day fasting or intermittent fasting – a minimum 16 to 24 hour fast) to any other diet method.
Exercise is not enough
here’s what each kind of exercise burns, in terms of calories
400 to 500+ per hour
Elliptical Training: Burns 575
Mountain Biking: Burns 545
Circuit Training (hard, with some cardio between sets): Burns 510
Cross-Country Skiing (moderate): Burns 510
Rowing (moderate, stationary machine): Burns 450
Swimming (freestyle laps, easy): Burns 450
300 to 400 per hour
Weight Lifting (dumbbells or machines): Burns 385
Hiking (without a pack): Burns 385
Walk-Jog Intervals: Burns 385
Body-Sculpting Class: Burns 350
Kayaking: Burns 320
Jazz Dance: Burns 305
Power Walking (very briskly, 4 mph): Burns 320
150 to 300 per hour
Flamenco, Belly, or Swing Dancing: Burns 290
Shooting Hoops: Burns 290
Golfing (walking and carrying clubs): Burns 290
Rebounding (jogging on a mini tramp): Burns 290
Water Aerobics: Burns 255
Tai Chi: Burns 255
Brisk Walking: (3.5 mph) Burns 245
Pilates (general mat workout): Burns 160
Yoga (Hatha): Burns 160
So, what does 500 calories get us ? 1 bowl of healthy poha (150 calories) + 2 slices of healthy multigrain bread (160) and small cup of cornflakes with milk (160 calories).
To reiterate – one hour of hard circuit training is going to be completely negated by a paltry breakfast. Oh and let’s be serious here – most of us get to 200 calories per hour (with brisk walks, jogs and yoga)
The hard fact is that exercise is superb for cardiovascular health, to build muscle, to build lung aerobic capacity and to even fight cancer (yes!). But it is not good enough to lose weight because it is virtually impossible to exercise more than what you can eat.
The EPOC argument – Excess post-exercise oxygen consumption or continuing-to-burn-fat-after-exercise
However, even those studies incorporating exercise stimuli resulting in prolonged EPOC durations have identified that the EPOC comprises only 6-15% of the net total oxygen cost of the exercise.
So 15% of 500 calories (in a one hour circuit training) is 75 calories = 1 slice of bread.
Conclusion – to lose weight, drop your calories : use any method you want – intermittent fasting, alternate day fasting (my current favorite) or 6 meals a day.
Exercise for overall health, power and strength.