Copyright (c) 2009 Neal Spruce
MYTH: 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 diets and low caloric intake leads to low energy levels ‘ meaning you burn less calories throughout your day and less intense workouts due to your lack of energy. This means more hunger; and as likely as not backsliding into binge eating and other unhealthy habits. 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: 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 eat smaller portions, eat slowly at meals and get a lot of exercise. 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. Ultimately, it doesn’t matter what you hear or what you read in the mass media. If you’re a fitness professional, you know that it all comes own to those notoriously immutable laws of nature. Calories (energy) in versus calories out determine whether you will stay the same, gain or lose weight. Those are the facts.
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] Børsheim E, Bahr R. Effect of exercise intensity, duration and mode on post-exercise oxygen consumption. Sports Med. 2003;33(14):1037-60.