Top 10 Weight Loss Myths

Losing weight – and most if it should be fat – is important for people who are overweight, in terms of body mass index (BMI) and waist circumference. It is also important for athletes, bodybuilders and recreational body shapers who want to get rid of those last few pounds.

With weight loss, it seems as if everyone has an angle, but most strategies are useless or insignificant.

Weight Loss Basics

What works for weight loss is to burn more calories in physical activity than you consume in food calories -- an excess of energy used compared to energy consumed. If you doubt this in any way, consider what happens to people on starvation diets in prison or who’ve been lost at sea or in the wilderness for many weeks or months with insufficient food. The body eventually uses all stored forms of energy, including muscle, to support itself for as long as possible. Then you die, mostly in a skeletal state.

But during weight loss (intentional or not), the body does try to prevent this happening — and this is a survival mechanism developed over several millions years of human evolution — by lowering its energy-burning rate in response to low-calorie consumption. The human body makes changes in all sorts of ways to adjust to changing circumstances. This is called “homeostasis.”

Variations exist in how much weight individuals can lose in response to diet and exercise, but in the end, changing energy balance is the only major thing that matters. I make this point because trivial approaches such as drinking green tea or eating chili peppers or drinking coffee (caffeine) or taking some herbal supplement or other may have a very small effect on fat loss that could easily be negated by the body adjusting to that challenge over time by altering its metabolism. Consistent deficits in energy intake and expenditure over months and years is what you need to concentrate on.

Here are 10 weight loss approaches that could waste your time:

1. Eat According to Your Metabolic Type

The origin of this idea in the modern diet business can be traced to The Metabolic Typing Diet by William Wolcott and Trish Fahey. The general idea dates from the 1970s and perhaps even before that.

The premise is that we all have a “metabolic type” — an individual metabolism that can be manipulated by dietary choices. According to this, we all fall into three metabolic types. And how do you know your metabolic type? Usually, the practitioners of metabolic type diets ask you a range of questions about your body shape, natural food choices, energy levels and many other things. Some may charge for blood or urine tests.

No doubt, you will soon be offered a genetic test that is supposed to identify your best nutrition and training habits based on your genes, which, presumably, create your metabolic type. Already similar services are being promoted to health and fitness enthusiasts — for a fee of course.

There is no evidence that metabolic types have any validity for weight management or fitness training, including weight training. Our genes can influence how our bodies works, but genes are not faultless determinants of physical function — or behavior for that matter. Genes interact with the environment, in this case, with food and physical activity. The idea that we have a metabolic type that reacts rigidly to diet in a certain way because of a genetic component is false, or at least only partly true. Food and exercise are just as likely to change the way these genes function as genes are to demand certain foods for health, perhaps even more likely.

2. Don’t Eat Carbohydrates Because They Turn to Fat

This one still persists, even after all the debunking that has been done. It is a persistent myth of misplaced emphasis that derives from the low-carb diet movement. First, some carbohydrates can be converted to fat and stored, but this is only significant if you overeat. Fructose in corn syrup and cane sugar is more likely to do this than glucose from starches, such as grains.

Second, even if some carbohydrate turns to fat, it is not permanently enshrined in some fat larder on your hips, legs, belly, arms and butt until the end of history. Mostly, you can burn it off just like you can burn off dietary fat that is eaten and stored. What matters is the total calories you consume and the energy calories you expend.

3. Eat Foods that Boost Metabolism or Decrease Appetite

While it is true that chemical substances, such as amphetamines, boost metabolism so that you burn more calories and this helps you with weight loss, amphetamines are powerful substances and few naturally occurring herbs or extracts have this type of effect. Or, if they do, products, such as ephedra, may not be safe for casual consumption. The FDA says ephedra is unsafe.

Other plant-derived substances touted as useful weight loss supplements are caffeine, capsaicin (chili), green tea, hoodia and many others sold as natural remedies. Some, such as hoodia, are supposed to be appetite suppressants.

The main issue with these weight loss solutions is that they aren’t solutions. Some may provide a small benefit, but mostly they cost you extra money and distract from the main game, which is getting your food intake and exercise plan working for you over the long term. There’s no harm in consuming coffee, chili and green tea as part of a normal diet. Spending big on supplements or exotic herbs for this purpose is bound to disappoint you if you don’t address the major factors in weight management.

4. Negative Calorie Foods Can Help You Lose Weight

This one is only for the very naïve. The idea that certain foods use more energy in digestion than they contain in calories is not to be believed, especially when lists of such foods includes fruits that contain significant calories in natural sugars.

If you eat a diet of green leafy vegetables and fruit, you probably will lose weight, but that’s because, overall, you will have reduced your calorie intake substantially. Try the Calorie-Count database to see how many calories are in various foods.

5. You Can Spot-Reduce Body Fat

This one is easy. No, you can’t. Spot reducing means targeting a particular body region for preferential fat removal, for example, doing crunches to rid your abdominals of extra fat. What you feel when you are doing crunches is muscle contraction and fatigue. The effort (energy expenditure) to create this is distributed across the body by increased heart rate, blood distribution and lung activity.

6. You Should Do Low-to-Moderate Intensity Exercise to Burn Fat

Low-intensity exercise burns more fat than glucose (blood sugar) as a percentage of total energy, and high-intensity exercise burns more glucose than fat. Even so, the total energy expended for a given time period is more important, because you can still burn fat at high intensity, even though the percentage of the total may be lower.

In addition, when you burn glucose doing high-intensity exercise, such as running fast or hard weight training, you empty your blood, liver and muscles of glucose, which then stimulates fat burning when you’re not exercising. You don’t have to exercise at a low-intensity to burn fat. Fat-burning “zones” were invented to sell treadmills and stationary cycles with electronic displays.

7. Low-Carb Diets Have a Metabolic Advantage

Just about all well-designed scientific studies on low-carb diets say that there is no such thing. Theoretically, diets with more protein should have a slight advantage, because protein makes you feel fuller, and it also takes a bit more energy to digest. This is a modest advantage, though, and likely to be insignificant in the long term, which is what 12-month comparison studies of low-carb diets have shown.

Low-carb diets may indeed be more effective for some people in the short term, but it will be because they impose calorie restriction on the dieter rather than providing any special fat-burning advantage.

8. Eat Many Small Meals Rather Than Three Big Meals

Many small meals, as opposed to three main meals, is supposed to enhance weight loss by making you feel full for longer. In a technical sense, this is supposed to prevent blood glucose from dipping low in between meals, which may cause you to become hungry and overeat during the next main meal.

Like many of the myths about fat loss, there is strong acceptance of this premise on many health and fitness sites. Weight trainers and body builders tend to be strong supporters of this idea. The problem is, there is no substantial evidence that it works. Even though a few early studies reported benefits, more recent evaluation has not found solid evidence to support this idea.

In fact, increased meal frequency may lower the “thermic effect of food,” which is the energy required to digest food. This would theoretically result in just the opposite of the outcome anticipated by the “small meal” supporters, showing a comparative increase in weight.

Even so, this idea is not as outlandish as some of the others, and more research may make the picture clearer. For now, though, you should not consider smaller, more frequent meals for weight loss as providing an advantage.

9. Weight Training is Superior to Cardio for Weight Loss

Generalizations such as these mean very little unless you measure the energy expenditure related to each activity. High-intensity activity will burn more energy than low-intensity activity during and also after exercise — the afterburn effect. High-intensity cardio would burn more calories than low- or moderate-intensity weight training. Actually, cardio generally burns more calories per unit of time, because the activity is constant, whereas weight training is intermittent, even though usually of higher intensity for short periods of time.

The best strategy is to do both cardio and weight training.

10. You Can Burn More Fat Exercising on an Empty Stomach

You probably can burn a lot of fat this way because fat is a preferred fuel when blood glucose is low after you have not eaten for a while. You will then go home, though, and eat a large meal to refuel, and you will burn less fat, because glucose will be replenished in the blood and liver. Over the course of 24 hours, you will have periods of preferential fat and glucose burning for energy, in different proportions. It balances out.

Blood glucose is low on an empty stomach when fasting -- first thing in the morning for example -- but you still need some glucose when you exercise. If you don’t eat before a workout session, you risk muscle protein being converted to glucose to maintain a critical level of blood glucose. It’s best not to do hard training on an empty stomach. A piece of toast or energy bar or fruit juice or sports drink is probably enough to give your blood glucose a little boost before you work out, which should prevent you using muscle for energy and still allow good workout energy expenditure.

Sources
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Foster GD, Wyatt HR, Hill JO, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med. 2003 May 22;348(21):2082-90.
Tai MM, Castillo P, Pi-Sunyer FX. Meal size and frequency: effect on the thermic effect of food. Am J Clin Nutr. 1991 Nov;54(5):783-7.
Taylor MA, Garrow JS. Compared with nibbling, neither gorging nor a morning fast affect short-term energy balance in obese patients in a chamber calorimeter. Int J Obes Relat Metab Disord. 2001 Apr;25(4):519-28.}