I recently read an article in the January-February edition of the WebMD magazine entitled “Your Body’s Inner Engine.” The article itself is actually okay, discussing the impact of sleep, protein, and weight-loss speed on your resting metabolic rate. (I’ll come back to summarize these points later in this blog.)
My approval came to a screeching halt, however, when I read a side section of the article entitled “Metabolism Demystified”. Here the author of the article, Brenda Goodman, cites work by researcher Kevin Hall, PhD, a researcher at the National Institutes of Health.
Here are three “myths about resting metabolism” the author identifies and endeavors to debunk:
Myth #1: “Eating more frequently, about every three hours, will rev the body’s metabolic engine.
- Informative point: digestion accounts for 10% of the calories your body burns in a day.
- The conclusion I disagree with: That it’s only the total calories you eat in a day that matters, and how you space them makes no difference.
- Dr. Liz comments: Allowing the liver and gut time to digest food between eating does matter; opinions vary on the benefits of eating every 2-3 hours (to avoid hunger) or every 4-5 hours (to allow for better digestion). At this time I don’t have a strong opinion on what the interval should be, but I do clinically and personally observe that some kind of eating structure to the day supports appetite control and successful weight management.
Myth #2: “You can blame midlife weight gain on a slower metabolism.”
- Information presented: “Up until age 50, metabolism slows [only] about 7 calories for each year of age.”
- The conclusion I disagree with: That age does not have a big impact on metabolism until your “senior years”.
- Dr. Liz comments: The majority of the women and men I take care of can attest to the role of hormonal decline that slows down metabolism. Dr. Hall’s numbers are probably based on the equation for a metabolic rate that does have age as a variable, but there are many hormonal variables that definitely slow down metabolism in midlife. Patients in their 40’s and 50’s (not the “senior years” mentioned in the article!) who say, “I am doing and eating everything the same and I am putting on weight” are not lying! And the solution is not the usual prescription of “eat less and exercise more”.
Myth #3: “Building muscle with resistance training will boost your metabolism.”
- Information presented: two pounds of muscle gained will result in burning 13 more calories per day at rest (i.e. while you are not exercising).
- The conclusion I disagree with: that 13 calories burned at rest per day per 2 pounds of muscle mass “is nothing” (it really says this!).
- Dr. Liz comments: I want to point out that muscle mass burns calories at rest – yes! while you are not even using these muscles. This effect is more pronounced in men than in women. In addition to more fuel-burning muscle tissue than women have, men also have, on average, more muscle mass than women do, which partly explains why men generally have an easier time managing their weight. Multiplying pounds of muscle times calories per pound of muscle does add up to a significant effect.
Let me summarize for you the parts of the main article that I do like. These points should sound familiar to you:
Not enough sleep leads to weight gain.
“People who don’t get at least six hours of sleep at night are prone to overeating, and they usually crave starchy, sugary foods.” One sleep lab study at the University of Pennsylvania showed that while appetite increases with sleep deprivation, resting metabolism slows down. Double whammy.
Your body is designed to hold on to weight.
Faster weight loss leads to a slower metabolism. Dr. Kevin Hall (from the NIH, mentioned above) studied contestants from the NBC show, The Biggest Loser. “By the end of the show, when [contestants] were at their lowest weight, their resting metabolisms had dropped by more than 600 calories per day, on average.” In other words, the intense exercise and calorie restriction over a relatively short period of time left these people with much less ability to burn fuel. Most of the show participants (13 of the 14) that Dr. Hall studied regained some of their weight and 4 of them got heavier after the show than they were before it started.
Protein intake supports weight loss.
Proteins are harder to digest than either fats or carbohydrates; the body burns more calories in the effort of digesting proteins. “The message for people looking to lose weight is that if you cut calories, don’t cut your protein intake.” Higher protein intake seems to raise the resting metabolic rate.
Let me leave you with this: When it comes to resting metabolism if you re-read each line above where it says “Myth”, you will see a statement that I think is actually true!