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Fact or Fiction? Enduring Fitness & Nutrition Myths

On Monday, September 29, 2008 by dotFIT experts

Elvis lives! There are alligators in the sewers. People love a good story. The more sensationalistic and absurd, the longer the myth seems to endure. In the health and fitness world, there are exercise and nutrition myths that have survived for decades, even though a preponderance of information proves their inaccuracy. As if the task of improving one’s health or fitness level isn’t challenging enough, fitness myths can cause confusion and frustration, and often result in wasted time. Here dotFIT experts debunk several fitness myths that seem to be particularly pervasive.

MYTH #1: Sugar is making America fat
FACT: Poor choices are making America fat

All legitimate science agrees that the causes of continuous weight gain in developed nations consists of a variety of environmental, psychological and physiological factors, not sugar and sweeteners . Researchers found that obesity was positively linked with time spent watching TV or at a computer and diets high in fat. This review looked at 38,409 individuals ages 20-74 and found no increase in body mass or obesity in populations that consumed sugar sweetened beverages vs. those that did not. Sweeteners are unfortunately guilty by association because of their presence in the foods and drinks (thus calories) we choose to consume. In other words, we can get fat on anything if we eat more calories than we burn, even if we only ate whole grains, fish and salads. According to a 2003 article in Obesity Research, “The use of caloric sweeteners has risen across the world, and has contributed to an increasing number of calories consumed per day, which leads to weight gain” . The sad truth is that as a society we simply make poor food and drink choices. No one would argue that a diet high in sugar (and high in the nutrient deficient foods that deliver it) is good for you, but in the end these poor food choices are simply a delivery vehicle for excess calories. And don’t forget, too much of any nutrient can become unhealthy, including, meats, vitamins and minerals, fish oils, etc. If we consumed sugars in moderation like we should, there would be no health-related issues. Sadly, we would probably fill the calorie gap with something else and then blame all our problems on the substitute food. So, there is nothing inherently fat-producing about sugar. The reality is that sugary foods do make up a significant portion of the typical American’s diet. Coupled with low daily activity, this is a recipe for disaster, tipping the scale in favor of weight gain. A more accurate take-home message is, “reduce junk food intake and increase physical activity to improve health and body composition”. Not, “don’t eat sugar, it makes you fat.”


MYTH #2:
High Fructose Corn Syrup (HFCS) makes you fatter than sugar and leads to type 2 diabetes
FACT:  Consumption of caloric sweeteners in America has declined since its peak in 1999 while obesity has climbed more rapidly than any other time in our history

This is an offshoot of the sugar myth. It’s just another urban legend, according to John S. White, Ph.D., a leading research consultant who specializes in nutritive sweeteners. “These allegations--such as increased fat production or increased appetite--are based on poorly conceived experimentation of little relevance to the human diet, which tests unphysiologically high levels of fructose as the sole carbohydrate, often in animals that are poor models for human metabolism.” Most of the anti-HFCS nonsense available to the public is based upon research showing the adverse effects of a diet unusually high in fructose, not HFCS. To clarify, HFCS is similar in fructose content to regular sugar. HFCS starts as corn syrup, which is primarily glucose. Through an enzymatic process, much of the glucose becomes fructose, making the syrup comparatively high in fructose when compared to regular corn syrup. White, granulated sugar is about 50/50 glucose and fructose. HFCS used in most beverages is 42% or 55% fructose, not significantly higher and maybe even lower in fructose than regular sugar (sucrose). The ratio of glucose to fructose in the American food supply has remained quite constant since the 1960s . To truly eat a diet high in fructose, one would have to go out of their way to do it and it would not be easy to do. Studies have looked at the metabolism of HFCS, its affect on insulin, appetite, leptin, and ghrelin and found no significant differences from sucrose (table sugar) .  It would be a simple argument if HFCS were the villainous substance many claim it to be, but consider that the rise in obesity in the US is mirrored around the world in all developed countries. HFCS is not a significant contributor of calories to the daily diet of countries outside of the US. In Latin American countries for example, soft drink consumption makes up a significant portion of total daily calorie intake, and obesity is on the rise, yet the makers of Latin American soft drinks still use good old sucrose to sweeten their beverages. In this case, it is the CALORIC contribution, coupled with decreased physical activity, which is increasing the region’s heft.

Regarding the safety of sugar and other sweeteners consider this: since the advent of HFCS (and remember the vast majority of the US population is consuming it), the average lifespan has increased by about two years (not because of HFCS, but clearly the substance is not systematically killing off the population). As for sugars, including fructose and HFCS, making us fat, the American consumption of ALL caloric sweeteners has been going down since its peak in 1999—to the tune of about 10 lbs. per year per person—while obesity during the same time period has climbed more rapidly than any other time in our history!

MYTH #3: What muscle you work determines where you lose fat (spot reduction)
FACT: Genetics determine where you lose fat

Let’s get right to the point: a muscle has no control over the fat between it and your skin. At some point everyone has tried to spot reduce. Plié squats for the inner thigh? Every ab device ever invented? Butt and gut classes? Fitness professionals are often asked questions such as

a) What is the best way to tone your legs, stomach and back?
It’s the word “tone” that confuses people.  What does it mean?  People think it means something like “create muscle definition”, but what they really want is less fat, and what is often overlooked is the fact that muscles become more visible by reducing the layer of fat that conceals them. No specific exercise will create muscle definition by removing fat from an area. So what’s the solution?  Lose body fat, and your muscles that are as hard and toned as any bodybuilder’s (however smaller) will be revealed. In other words, simply consume fewer calories than you burn until your fat levels are reduced to your satisfaction. All that said, weight training can add muscle so that when you lose fat your body has more pronounced lines or muscle definition. Larger muscles may help accentuate the body’s natural contours.

b) How can I get rid of the excess fat around my thighs specifically? You can’t. Consider this: your thighs generally move more than any other body part but the fat still ends up there. As you maintain a calorie deficit (eat less than you burn), body fat will leave from whatever area your body was genetically programmed to draw it from at that point in time. As a rule of thumb, the last place on is the first place off, but this can change as you age. And again, if you consistently consume fewer calories than you burn, that stuff on your thighs will go, it just might be the last to do so.

A word of caution--many exercisers, in an attempt to accelerate the loss of fat from a trouble area, will launch an all out exercise attack on that area. Performing a high volume of resistance training for an area that is viewed as fat or bigger than one likes may have the undesired affect of increasing muscle size (called hypertrophy) in that area. If caloric intake is sufficient (and it often is), and body fat is not being lost systemically, then the area of focus can increase, pushing the fat over it farther out.


MYTH #4:
If your goal is body fat reduction, you’ll burn more fat in your target heart rate zone; if you go over it you will burn muscle
FACT: If you’re maintaining a calorie deficit, then the harder you work the more calories you’ll burn and the faster you’ll lose fat

Let’s look at the evolution of this myth. Heart rate zones and tracking intensity were measures designed to aid endurance athletes. This was to ensure that an athlete did not work at a rate that would cause them to prematurely fatigue. If the athlete worked at too high an intensity, they would deplete their muscular CHO stores and “hit the wall” which impedes performance. Training in the proper “zone” ensured that muscular carbohydrate would not be depleted and that activity could continue for the required time or distance.

At rest, our bodies are primarily burning fat. As the intensity of activity begins to increase, so does the contribution of muscular and systemic carbohydrate. At about 20% VO2 max, fat contributes 60% and CHO 40% of the energy used. This contribution equalizes (50/50) at about 35% VO2 max. By 70% of VO2 max, CHO makes up 80% and fat 20% of the energy used to fuel activity . So, while it is true that fat makes up a bigger contribution of calories burned at a lower intensity, this has no application to a weight loss client. Fat or weight loss is ensured by being in a caloric deficit. The practical goal for the typical exerciser is how to maximize their time working out, so as not to “live in the gym”. At a higher intensity of exercise, more calories, and usually even more fat, are burned. Period. Additionally, there is a phenomenon called EPOC (excessive post oxygen consumption) that indicates a higher rate of fat usage for many hours after the exercise session, BECAUSE of the exercise session. EPOC is directly correlated with higher intensity exercise. Ultimately, you would have to exercise for twice as long at a lower intensity as you would at a higher intensity to get the same degree of calorie burn. As for muscle being burned, that is influenced by total caloric intake, availability of glucose and duration of activityv. It can be a good thing if muscle is called upon to supply energy needs for the body as this leads to new muscle growth, just as weight training disrupts muscle tissue and leads to growth. In both instances, exercise served a stimulus to “damage” muscle, leading to a rebuilding response.

In summary, exercise itself does not burn a significant amount of fat. It is the contribution of exercise to a person’s total daily energy expenditure, including the intensity, that affects overall fat loss . In other words, exercise simply adds to your daily calorie needs, so do all you can during your workout time because the longer and more intensely you move, the greater the amount of calories you burn, leading to a greater fat loss. And the less fuel you put back in, the more must be drawn from your fat stores during the non-workout portions of your day.

MYTH #5: Eating a diet that is too low in calories will cause the body to go into starvation mode and not burn any calories
FACT: Severely cutting calories will cause the metabolism to adjust slightly, but not enough to prevent fat loss

Remember that people around the world who truly die of starvation are not overweight when they expire. It’s true that when you severely cut calories your metabolism will make a slight adjustment, allowing your body to run on fewer calories—but it’s not a large compensation. If you need to lose weight and you are not, eat less and/or move more and forget about slowing your metabolism.

That said, the point is not to lose weight too quickly by drastically reducing calories because that method is generally not sustainable. Second, although there is a slight down regulation in metabolism in response to a very low calorie diet, the main reason it may appear to slow down more than it actually does is because the extremely low calorie intake is slowing YOU down. In other words, you become less energetic, forcing a reduction in your daily activities, therefore burning fewer calories overall. Crash dieting with excessively low calorie intake leads to low energy, so you burn fewer calories all day and work out less intensely. This leads to increased hunger, which in turn increased the chances of rebound and binge eating behavior. This can result in a calorie intake that temporarily exceeds your pre-diet intake, leading to a rapid re-accumulation of weight. This is easily misinterpreted as the results of a “damaged” metabolism. It is worth noting that any temporary, minor reduction in metabolic rate due to excessively low caloric intake is regained once caloric intake is increased. Your metabolism is not damageable. Take home message: Never blame failure on metabolism, no matter what anyone tells you! Simply move more.


MYTH #6:
Naturally skinny people have faster metabolisms, so they don’t have to exercise and can eat anything they want
FACT:  Naturally skinny people consistently burn as many calories as they consume

Individual metabolisms do vary, but not much. And people who stay slim and eat anything they want either don’t want much (total calories) or move enough (daily activities including fidgeting) to cancel whatever they eat. In other words, people who are overweight eat too much relative to how much they move, whether they exercise or not. People who stay thin and don’t exercise eat as much as they move. Those who tend to stay thinner have the habits that overweight people need to adopt. They tend to eat more slowly, eat smaller portions and move continuously. The calories in are countered by the calories out. In fact, the heavier you are (no matter who you are) the more calories your body burns. So put that heavier, more calorically expensive body to work and get moving! More weight in motion means more calories burned per unit of time.

Final note on metabolisms and plateaus: The “fast and slow metabolism” thing has become a bad excuse for many people. Anyone can get their daily calorie burn (overall metabolism) as high as they need by simply moving or standing more. The main reason the body comes to plateaus during dieting or exercise (besides cheating) is that when weight is lost you become fit, your body uses fewer calories to perform the same work (because it’s easier than when you were heavier and out of shape), forcing you to add work or eat less in order to continue to progress .

People who eat well and exercise regularly (and are “tapped out” as far as time or cutting calories) is to simply increase your daily movements at home or at the office. Stand instead of sitting. Pace the room while on the phone or thinking. Take stairs instead of elevators or escalators. Park further away. Take a walk at lunch. Walk to a colleague’s office to talk rather than using e-mail or the intercom. Additionally, you can try changing your workout, including the type of cardio you perform, which may help temporarily fire up your metabolism .

So there you have it. You can now take these myths off your list and get on with your fitness goals. Most people know in their heart that these myths can’t possibly be real, but then there’s another segment on the news or an article in a “health” magazine that makes these myths sound plausible. Relating weight control back to calorie balance may not be as sensational as the idea of damaged metabolism, but it’s the truth. At the end of the day, no matter what the news and magazines say, fitness professionals are left with the simple truth that body weight and appearance are controlled by the laws of science and thermodynamics (the science of energy relationships). Calories (energy) in versus calories out determine whether you will stay the same, gain or lose weight. Those are the facts.

References
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7. Saris WHM, Schrawen P. Substrate oxidation differences between high- and low-intensity exercise are compensated over 24 hours in obese men. Int’l J of Obesity. 2004; 28:759-765.
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9. Amati F, Dube JJ, Shay C, Goodpaster BH. Separate and combined effects of exercise training and weight loss on exercise efficiency and substrate oxidation. J Appl Physiol. 2008 Jul 10. [Epub ahead of print]
10. Børsheim E, Bahr R. Effect of exercise intensity, duration and mode on post-exercise oxygen consumption. Sports Med. 2003;33(14):1037-60.
                                                     

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