What Would we Do without Experts?We've all heard the conventional expert advice to lose weight by eating less and exercising more. It seems to make sense: if you eat fewer calories, your body will have to burn some of its own fat. Or if you burn more calories by exercising, your body will have to burn some of its own fat. Calories in, calories out. Just look at serious athletes or starving people in Africa.
And yet like a lot of things that look good on paper, this doesn't seem to work out in real life. In Why We Get Fat(1), Gary Taubes points out several groups of people who were hardworking, malnourished, and generally overweight. At one time, he adds, obesity was considered a disease of malnutrition.(2)
But wait, maybe the calorie-restricted mice sat around a lot more. Indeed, they did:
If you've ever tried and failed to lose weight by eating a little less and exercising a little more, you're not alone. Several years ago, I started Body for Life, a program that involves exercise and eating a lot of protein and carbohydrate. I ate more than I had been eating and lost weight. After a few years, I noticed I'd gained weight, so I cut down on my cheating (I stopped drinking Coke), and I kept gaining weight. I cut out the sixth small meal of the day, and I kept gaining weight. I was diligent about workouts. By the calories-in, calories-out theory, I should have gained weight eating more and lost weight eating less.
The Case of the Underfed Mice
In a recent study(3), researchers fed a group of mice ad libitum (as much as the mice wanted). The fed another group of mice (the calorie-restricted mice) only 95% as much feed as the other group ate. Result of the three-week experiment:
Five percent CR induced significant changes in body composition without altering body weight. Body weight was relatively stable throughout the experiment in both AL and CR mice (P > 0.05). Relative to AL mice, CR mice showed an increased body fat mass (P < 0.01) and decreased lean mass over 3 weeks. CR mice had a 43.6% greater fat mass (4.97 ± 0.40 g vs. 3.46 ± 0.15 g, P < 0.01), and a 6.4% lesser lean mass (14.44 ± 0.17 g vs. 15.43 ± 0.26 g, P < 0.01) than AL mice at the end of the experiment.Result of the four-week experiment:
Five percent CR induced a significant increase in body fat mass (P < 0.01) and a significant decrease in lean mass (P < 0.01), whereas AL mice remained relatively stable over 4 weeks. Relative to the AL mice, CR mice had a 68.5% greater fat mass (3.37 ± 0.23 g vs. 2.00 ± 0.09 g, P < 0.01), and a 12.3% lower lean mass (14.43 ± 0.24 g vs. 16.45 ± 0.31 g, P < 0.01) at the end of the treatment (Figure 1a)
TEE (total energy expenditure) (kcal/day, P <>TEE was 5.0% lower (7.97 ± 0.14 kcal/day vs. 8.38 ± 0.46 kcal/day) and REE was 20.7% lower (4.83 ± 0.54 kcal/day vs. 6.09 ± 0.43 kcal/day) in CR mice than AL mice after 3 weeks (Figure 3).
Considering that the CR mice had a 44% greater fat mass than the AL mice after three weeks on their diet, it would have taken a heck of a lot of time on the exercise wheel to burn off that fat.
Why did the CR mice get fat on fewer calories? Their metabolism (the way their bodies use fuel) dialed down. More of the nutrients were sent to fat cells. As a result, they didn't have as much energy to get up and move. Perhaps this is an evolutionary response to food shortages.
Weight Gain, Weight Loss have More than One Cause
What about anorexics and anyone else who restricts calories--why don't they put on weight? They restrict calories a lot, not a little. Weight loss programs like Nutrisystem and Jenny Craig work, at least in the short term, because they set calorie consumption at concentration camp levels.
Is weight gain necessarily caused by undereating? Of course not. It seems there are several causes of weight gain: hormones, medications, and my fave, too many carbs, all play a role. Just as there is more than one way to lose weight (severe calorie restriction, macronutrient balance, micronutrient balance, illness), there is more than one way to gain weight.
For Further Reading:
The basics on a diet that will let you lose weight without restricting calories: the Atkins Diet. This is the diet I've followed for a year. I lost 20 pounds and a number of health problems, improved my lipids, and I'm never hungry.
Tom Naughton's take on the calorie-restricted mouse study:
Dr. William Davis got not only fat but diabetic while hungry and exercising. It looks like those CR mice knew what they were doing by lying around.
A blog post from Weight of the Evidence that includes links to further studies on weight gain and malnutrition:
Mike W's NINO (nutrients in, nutrients out diet):
1. Why We Get Fat by Gary Taubes, pp. 19-28.
2. Ibid, pp. 29-30.
3. Obesity, "Mild Calorie Restriction Induces Fat Accumulation in Female C57BL/6J Mice" by Xingsheng Li, Mark B. Cope, Maria S. Johnson, Daniel L. Smith Jr and Tim R. Nagy. Published online October 1, 2009.