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How to Lose Weight: An interview with Dr. Theodore VanItallie
Tuesday, September 07, 2004 11:00 am Email this article
Theodore B. VanItallie has been studying obesity for nearly 50 years. Larry Hobbs interviewed Dr. VanItallie by phone.
Hobbs: Tell me a little about your background and how you became interested in obesity?
VanItallie: After I completed my residency in internal medicine I had 2 years of post-doctoral research training at the Harvard School of Public Health in the department of nutrition. One of the main interests of that department was obesity.
Hobbs: Explain the difference between quality and quantity of weight loss.
VanItallie: Quality of weight loss is the composition of that loss, while quantity, obviously, is the amount or rate of weight loss.
Hobbs: What is considered good quality weight loss?
VanItallie: A loss that is at least 75% fat and no more than 25% fat-free mass. That is the approximate composition of excess weight.
Hobbs: What determines the quality of weight loss?
VanItallie: Three things. 1) The calorie content of the diet. 2) The protein content of the diet. 3) The patient’s body composition.
A calorie deficit that is too large, causing too rapid weight loss, results in an excessive loss of fat-free mass.
A person also has to maintain an adequate protein intake to prevent protein depletion. And a heavier person is able to tolerate a very low calorie diet for a longer period of time than a lighter person.
Hobbs: What is the effect of diet composition on weight loss?
VanItallie: It makes sense to reduce the dietary fat, because in rats it has been shown that a high-fat, low-calorie diet causes a greater retention of body fat during weight loss than those fed a low-fat, low calorie diet. But this needs to be tested in humans.
Hobbs: How much dietary protein do you recommend?
VanItallie: One gram of high quality protein per kilogram of desirable body weight. This would be 70 to 100 grams per day for most people.
Hobbs: What are the side effects of protein depletion from too little protein?
VanItallie: At the extreme, if consumed over a period of months, a very-low-calorie diet with a long-term protein content of less than 34 grams per day can cause heart arrhythmias and death.
Several years ago at least 68 people died while on or shortly after being on a liquid protein diet for two to eight months. This was probably caused by a protein deficiency because the liquid collagen protein that they used was a poor quality protein.
Less serious side effects include nausea, vomiting, diarrhea, constipation, fatigue, orthostatic dizziness, cold intolerance, dry skin, brittle nails, hair loss, muscle cramps, amenorrhea, decreased libido, euphoria, insomnia, anxiety, irritability, depression, and formation of gallstones.
Protein depletion can also reduce strength, endurance and immunity.
Hobbs: What are sources of good quality protein?
VanItallie: Egg whites, milk products, and lean cuts of meat and fish.
Hobbs: How much dietary protein is too much?
VanItallie: I don’t know that the effects of higher protein diets have been adequately studied. A higher protein intake can’t be tolerated by people with kidney or liver disease, but there is no evidence that such a diet is harmful in people who are healthy.
Hobbs: What is the maximum rate at which a person should lose weight?
VanItallie: As a rule of thumb, one-percent of body weight per week, which would be 2 lbs per week for a 200 lbs person.
VanItallie: Losing weight faster than this can cause excess loss of fat-free mass [muscle].
For example when people lost weight at a rate of 0.28 lbs per day which is 2 lbs per week the composition of weight loss was 85% fat and only 15% fat-free mass.
When the rate was 0.32 lbs per day or 2.25 lbs per week the composition was 75% fat and 25% fat-free mass.
Increasing the rate to 0.45 lbs per day or 3.15 lbs per week the quality of weight loss decreased so that patients were losing an equal amount of fat and fat-free mass.
The quality of weight loss further decreased to being only 25% fat and 75% fat-free mass at a rate of 0.77 lbs per day or 5.4 lbs per week and only 15% fat and 85% fat-free mass at a rate of 1.09 lbs per day which is 7.6 lbs per week.
This is why it’s so important to lose weight slowly. So that you lose mostly body fat and maintain fat-free mass [muscle].
Hobbs: What kind of calorie restriction do you recommend?
VanItallie: Morbidly obese people can tolerate very-low-calorie diets better than those who are moderately obese.
Calorie intake should never go below 500 calories per day and probably not below 800 calories.
The calorie restriction should be made to limit the rate of weight loss to 1% of body weight per week.
Hobbs: Why do you think Americans are getting fatter?
VanItallie: The obvious things would be that we’re eating too much and exercising too little.
Larger portion sizes, snacking and low-fat foods encourage eating more.
It has been estimated that up to 25% of our weight gain may be due to smoking cessation.
There might also be a shift in our population base, such as more Mexican-Americans who seem to have a predisposition to gaining weight.
Hobbs: How do you feel about the use of weight loss medications?
VanItallie: They should be reserved for patients who are seriously overweight and who have failed to lose weight by diet and exercise alone. Those who have comorbidities such as hypertension, type II diabetes, coronary heart disease, gout, and arthritis are good candidates for treatment with antiobesity drugs.
Hobbs: What are your overall recommendations to patients who are trying to lose weight?
VanItallie: Nutrition education is important. People who are the least educated tend to be the heaviest. Primitive man had to hunt for food, but now man is hunted by food. We need to develop strategies of “defensive eating”.
Hobbs: Why do you think there is such a large difference in the prevalence of obesity between black and white females?
VanItallie: It is probably that, on average, black females are less educated and have a lower socioeconomic status than white women.
Both education and socioeconomic status are inversely associated with obesity. Genetics is probably also involved.
Hobbs: You noted that in the Nurses Health Study leaner women exercised more, consumed more alcohol, and were more likely to take hormone replacement therapy. Do you think there is a causal relationship between these?
VanItallie: Obviously increased exercise causes women to be leaner, but I don’t know about consuming more alcohol or taking hormone replacement therapy.
It may just be that more educated women, who are also more likely to be thin, drink more and are more likely to take hormones.
We know that hormone replacement therapy can help prevent the accumulation of abdominal fat that occurs after menopause.
Hobbs: In your paper you pointed out that the French have not gained weight in the last 10 years. Why is this?
VanItallie: This is just speculation, but maybe it’s because they walk more and smoke more, their portion sizes are smaller, they don’t snack as much, and they don’t eat as much fast food.
Hobbs: Regarding your most recent paper on the Prevalence of Obesity why do you think there was such a large increase in obesity in the last 10 years in men aged 50-74 and in women aged 40-60?
VanItallie: I really don’t know. Smoking cessation may have something to do with it. It’s possible that some of it may be a sampling problem.
Hobbs: You also wrote that Italian men are a lot heavier than women. Why is this?
VanItallie: That surprised me also. The only thing I can think of is that maybe the women are more active.
Hobbs: [A well-traveled friend made the same observation about several Mediterranean countries including Italy and Turkey. That is, the women tend to do more work while the men tend to do more sitting around.]
Dr. VanItallie can be reached as follows:
Theodore B VanItallie, M.D.
PO Box 775
Boca Grande, FL 33921
(941) 964-0747 fax
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