Is dieting hopeless? Monica takes on a "skeptic"
In a recent post, I offered some advice to a reader who wrote to ask how many calories she should eat if she wanted to lose weight. I recommended that she aim to create a calorie deficit of about 7,000 calories per week (by reducing caloric intake AND increasing physical activity), which would lead to losing approximately two pounds a week.
Over the weekend, a reader ("Skeptic") posted a detailed critique of my post, charging that it was an "oversimplification" of metabolism and containing "a lot of inaccurate information." (You can read his entire comment on the original post.)
Input from readers is always welcome, and often adds valuable information to the dialogue. And I completely agree with Skeptic on some points. Fuel metabolism is complex, and we often simplify things in order to make the ideas easier to work with. For example, the equation "cut or burn 3500 calories to lose one pound" is a simplified (but still useful) approximation.
But several of Skeptic's points are worthy of further discussion.
1. Skeptic argues that basal metabolic rate (BMR) is "virtually independent of energy intake." "If you reduce your dietary input," he states, "your metabolism will NOT decrease."
I disagree. BMR is regulated by many factors, including thyroid hormones. When there is a sustained decrease in caloric intake, thyroid hormone levels are surpressed, which lowers BMR. (Reference) This is an adaptive mechanism that helps the body survive under conditions where food supplies are low. It's also a well-known frustration for dieters (and those suffering from hypothyroidism).
2. The validity of set-point theory has been challenged by recent data. (Reference) At best, the "set-point" may be one of many factors that may affect body weight--and these factors affect different individuals in different ways.
3. The theory that the hormone leptin, which is released from fat cells, regulates obesity by sending a signal to the brain that reduces hunger has also been disproven by recent research. (Reference)
4. Skeptic makes a fascinating argument I hadn't heard before. He claims that obese people have higher metabolic rates than lean people because it takes more strength to move a fat body and the obese therefore have larger muscles. Even if this is true, it says nothing about how an individual's BMR changes in response to changes in energy intake.
Finally, Skeptic points out that "about 90% of people that lose weight will gain in back within 5 years."
That may be true. We all know that permanent weight loss is hard and that many people--even most--fail. But the whole idea behind NutritionData.com is to improve those odds by offering information, tools, support, and guidance that empower you to reach your goals. Maybe that's why NutritionData users regularly beat the odds, by losing weight and keeping it off. Better information + better tools = better results.
If losing weight is one of your goals, be sure to check out our brand-new Diet and Weight Loss Center, with new content and features focused on helping you achieve your weight loss goals--all powered by NutritionData.com's unparallelled nutritional analysis tools.
