Liquid Diets Make You Thinner but May Pose Big Fat Health Risks
updated 04/23/1990 AT 01:00 AM EDT
•originally published 04/23/1990 AT 01:00 AM EDT
Liquid diets, which are available over the counter and in doctors' offices, have been around for at least two decades (60 deaths were attributed to early "liquid protein" versions deficient in nutrients). Do they work as miraculously as they seem to? Dr. Thomas Wadden, a psychologist at the highly regarded Obesity Research Group at the University of Pennsylvania School of Medicine, uses the diets in his work with obese patients and recently co-authored an article on the diets' hazards in the Journal of the American Medical Association. Correspondent Andrea Fine spoke with him in his suburban Philadelphia home.
What exactly are low-calorie liquid diets?
There's an important distinction between low-calorie and very-low-calorie liquid diets. Low-calorie liquid diets, which are generally available over the counter, are intended to replace no more than two meals a day, with a total daily consumption of at least 100 calories, including a well-balanced solid meal. Very-low-calorie liquid diets provide between 400 and 800 calories a day and should be used only in a medically supervised program.
Are the very-low-calorie diets safe?
Yes, when used by people who are at least 40 lbs. overweight and when supervised by physicians trained in administering the diets.
Are they successful?
They definitely can be. Obese people who need to lose 40 lbs. or more can do so very quickly. In 12 weeks, for instance, men with an average weight of 250 lbs. can lose about 50 lbs. In 12 weeks on a standard, 1,200-calorie diet, the man will lose only about 20 lbs.
What is the downside?
At 400 to 800 calories a day, you can expect to feel some sluggishness and fatigue at first and possibly some muscle cramping. In winter you'll feel very cold because your metabolism slows down. Since you lose a lot of bodily fluids, you need to drink two or three quarts of water a day to prevent dehydration. And you might feel faint or light-headed on occasion. Moreover, the hard part is keeping the weight off. Without behavioral and nutritional counseling, most people regain 67 percent of what they've lost in a year.
A House subcommittee is currently investigating the diet industry. What do you think will he the outcome?
I think it will show how poorly the whole diet industry is regulated and how important expert medical supervision is for anyone hoping to lose more than 2 lbs. a week.
Do you recommend very-low-calorie diets for mildly overweight people with only 5 to 30 lbs. to lose?
No, and in fact they can be dangerous. The safety of these diets has been tested only in the seriously obese. A mildly overweight person is likely to lose more muscle or lean body mass, which could result in heart problems and damage to other organs.
What about over-the-counter liquid diets?
These diets can be used by the mildly overweight, but it's essential they follow the recommended guidelines. The diets can be dangerous if used to replace all meals.
What options do you suggest for the mildly overweight?
Small changes in eating and exercise habits and gradual weight loss. I'd suggest you eliminate 500 to 700 calories a day. Cut down on sugar, butter, oils and fried-fat foods. Stop drinking sodas. Two non-diet sodas a day are almost 300 calories. If you did these things, you'd lose about 1 to 1.2 lbs. a week. Then you should increase your activity—for instance, get off the bus five blocks early and walk, and climb stairs instead of taking elevators.
Say you've lost a lot of ugly fat on a very-low-caloric liquid diet. Now what?
It's tough. When you're losing weight, you're avoiding all the foods that gave you problems and consuming only the liquid diet. It's far easier than trying to eat in a controlled fashion. When you're off the diet, all your old behaviors may reappear, and the weight starts coming back. When people regain 4 or 5 lbs. they think, "My God, I haven't learned anything. I'm doomed to failure again." Before they realize it, they've gained 20 lbs. We try to teach people how to reverse small weight gains as they occur. But they have to modify their life-styles—in particular, eating, exercise and dietary habits. They need to spend at least four to six months in a maintenance program with a physician, behavioral counselor and dietician. There should also be group sessions with other dieters.
This all sounds very expensive.
Yes, it's going to cost you about $50 per lb. for a medically supervised, very-low-calorie liquid diet. So it'll probably cost between $2,000 and $3,000 to lose 50 lbs. Some people will say you don't need all those professionals, but it can cost you more in the long run if you damage your health or gain back all you lost.
And there are no real cures?
Right. A patient must realize serious obesity can never be cured, only managed. It's like jogging—you can't go out running for six weeks and expect to stay in good shape for the rest of your life.