May 06, 2007
Should Older Obese People Diet?

A research team at Wake Forest University Baptist Medical Center found obese old women who diet and lose weight maintain or increase their mobility.

Her study evaluated 23 obese, postmenopausal, sedentary women with a mean age of 58 who participated in the DEMO study. For five months, their meals and snacks were provided by the study and contained 400 fewer calories than they needed to maintain their weight.

Participants’ body composition and physical function were measured before and after the five-month period. Tests of physical function measured knee strength, hand-grip strength, walking speed, aerobic fitness and ability to quickly rise from a chair without using their arms. The women lost an average of 25 pounds, with muscle representing about 35 percent of the total loss.

“Despite the large amount of muscle loss, their aerobic fitness and their ability to rise from a chair showed a trend toward improvement,” said Demons. “Their strength and walking speed did not change. This suggests that their weight loss through dieting wouldn’t be expected to lead to increased disability.”

So far, so good. But the overwhelming majority of people who lose weight regain it. Well, they regained proportionately less muscle than they lost.

Lyles’ project evaluated 30 women from the DEMO study to determine body composition when weight was regained. Body composition was measured before and after the five-month period of calorie restriction. A third measurement was taken 12 months later.

The women lost an average of 25 pounds – about 32 percent of the lost weight was muscle and 68 percent was fat. The women regained an average of 11 pounds. About 27 percent of the regained weight was muscle and 73 percent was fat.

35% of their loss was muscle. But only 27% of their gain was muscle. That's not good. Some of that could be due to aging. But it seems too large a change to attribute only to aging.

I'm skeptical of the benefit of dieting for these women. Almost all of them are going to regain most or all the lost weight. Dieting might be worse than not dieting. Exercise to build up muscle mass might provide a clearer benefit. I'm skeptical that people can defeat the appetite regulation mechanism in the brain which starts telling them to eat more when they get their weight down. We need drugs that reduce appetite or for most people weight loss diets are going to do more harm than good.

Share |      Randall Parker, 2007 May 06 11:01 PM  Aging Diet Studies

spencer said at May 7, 2007 12:29 PM:

If you start out at 100 and lose
35% that takes you to 65.
If you regain 27% of that
you go back to 82.55,
for a net loss of about 17%.

SpakKadi said at May 8, 2007 10:55 PM:

spencer, you're thinking percent gain, not percent OF gain. The gain is 11. 27% of the GAIN is muscle gain. They didn't gain 27% of their weight in muscle. That would be a lot more than 11 pounds. And a lot of muscle.

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