Let’s talk about calorie myths

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May 19, 2013

Let’s talk about calorie myths

Welcome to my first entry on our website.

Where to begin?? I thought I’d start by presenting some misunderstood ideas about calories as they relate to exercise and weight loss. The National Institutes of Health (NIH) funded a review of these unsupported beliefs. The results were reported in the New England Journal of Medicine in January, 2013. Many of the issues covered in this report are the same ones that my patients ask about on a regular basis.

SO here we go. The first conundrum is, if I walk every day, why can’t I lose weight – why doesn’t my weight follow the 3500 calorie rule? In another entry, we’ll talk about controversies regarding the rule itself. But, here’s what the rule says: that every 3500 kcal (‘calories’ as listed on food labels) equals one pound. If you eat 3500 extra calories without increasing your activity, you will gain a pound. If you exercise until your favorite treadmill, elliptical, exercise monitor, whatever, says you’ve burned 3500 calories, you will lose a pound. The number of calories you burn doing a certain activity depends on what the exercise is and how much weight you are carrying while doing it. Medical literature always uses a 70kg (154 pound) person as their example, so we’ll do the same. If you are a 150 pound person and walk a mile per day, depending on the speed and incline, you might burn about 100 calories. In theory, if you walk 1 mile daily for 35 days, you should burn 3500 extra calories. You should lose 1 pound. If you were disciplined in your routine for 3 years, that would repeat that 35 day cycle 30 times, and you should lose 30 pounds, assuming you don’t eat more calories. That just doesn’t happen! Why not?

There are several reasons, but here are a few of the main ones. There is a lot of individual variation in how we burn calories. Everyone knows someone who can tear into a package of double-stuffed Oreos without gaining an ounce. Let’s just decide that people like that are annoying, and move on. For the rest of us, as we exercise, our muscles become more efficient (more on that in later blog entries) and we need to do more work to burn the same number of calories.

There is likely also a control mechanism that kicks in that served us well in the past, but in our current age of calorie-overload is detrimental. Ages ago, when we start to lose weight, our brains were signaled that we were in danger of starvation – which might have been true when we were hunting and gathering. Weight loss in those times usually meant that food was not available. That signal is related to the hormone leptin that is secreted by our fat cells. So the body preserved itself when food was scarce by slowing down our metabolism to keep the fat we had. This slowing of metabolism in response to weight loss is felt to be contributory to the yo-yo pattern of weight loss and gain that so many people experience. Once they lose weight, their metabolism slows down, so they gain weight, the metabolism re-adjusts, enabling them to lose weight more easily, and so on. Bottom line – If you continue to do the same activity for months or years on end, it will no longer have the weight loss effect it did at the beginning.

The second commonly held belief that was dispelled in this NEJM report was that setting realistic goals is important in avoiding frustration with your weight loss plan. Not true, evidently. Set your goal wherever you wish — realistic or not — and go for it! Period!

Myth number three – people who lose weight faster at the beginning are more likely to gain it back. The fact is, many people re-gain weight, no matter how quickly or slowly they lost it. I will offer this advice, though, from my clinical experience. I find that when patients are on extremely low calorie diets, no-carb diets or using only pre-packaged meals, they are less likely to maintain the weight loss. I believe they never learn to shop for and prepare healthy foods that will satisfy them and help them change their lifestyle. Eventually, habits that need to be changed include everything from what you buy at the grocery store and which foods you prepare, to bringing lunch to work and finding time in your daily schedule to exercise. So, using a weight loss method that includes changing these habits usually leads to slower weight loss, but increases the chance you’ll be more successful in the long run. In addition, when weight is lost too rapidly without attention to proper nutrient balance and exercise, there is muscle loss. Losing muscle mass is not a good thing for your overall health. From the weight loss perspective, it’s not good either. Muscle burns more calories than fat tissue while you are at rest. The more muscle mass you have, the more calories you burn on any given day, for the same amount of activity. So muscle loss means fewer calories burned by your body on a daily basis. This undermines your attempt to lose weight! Therefore, including exercise in your weight loss program, both cardio and strength training, makes weight loss easier and more sustainable, both by burning calories at the time of the exercise and by building muscle. In future entries, we’ll address how to burn more calories in the same amount of exercise time.

Finally, sorry to burst your bubble, but evidently there’s a myth out there that says a ’bout’ of sexual activity burns 100-300 calories per person. We won’t ask who’s applying the monitors here, but somewhere along the line it was determined that this activity burns 3 metabolic equivalents (METs), about 3.5 calories per minute or 210 calories per hour, for a 150 pound person. This is about the same rate of calorie burning as relaxed walking. In practice, however, the number of calories might be anywhere from 3 to 300. No further explanation, just don’t count on the 300. That’s all I’m saying.

Well, that’s all for today. In time, with our wonderful network of professionals, we hope to share with you our love for learning, fitness, great healthful foods and appreciation of the mind-body connection. Please join us and provide us with your questions and join us on this journey for a better informed, healthier, happier you.

With each blog entry, I’d like to leave you with a healthy recipe. This one is as simple as it gets: for a lunch you can prepare at work, cut up an apple and spread a little natural peanut butter on it – no sugar or salt added. If you’re not as concerned about the calories, put it on whole wheat toast. Or for a snack, put the peanut butter on celery – It’s filling and nutritious —

Talk to you soon —

1. Casazza, et al.: Myths, Presumptions, and Facts about Obesity. NEJM 2013; 368:446-54.


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