Womens Health

Weight Loss Diets and Supplements: Basic Principles

Frederick R. Jelovsek MD, MS

"Some friends of mine are on the diet program Herbalife ®. They say it is dr. approved and it seems to be working for them. What is your opinion of this program?" Anonymous

I cannot say for sure about Herbalife's dietary program because I have not had any experience with it and there are no publications I could find of scientific studies using the program. It appears from web publications that it is composed of protein liquid supplements, herbal supplements and "fat burner" supplements. It was very difficult to find what components are in each of the different formulas and products. The "fat burner" product or "cell activator" contains ephedrine (in the herb Ma Huang). This is a central nervous system and blood pressure stimulant.

Chronic use in high doses can produce cardiac problems. That doesn't mean that this product has a problem, it just means that you have to read the labels very carefully and will have to determine if there are any dangerous components in it. Remember that the FDA (Federal Drug Administration) does not require testing of these products.

Various diet programs surface from time to time. I think that each one needs to be evaluated first of all to make sure there are not harmful components and secondly to evaluate if there are likely to be any added benefits above just taking a cheap sugar pill (placebo). The best way that you can be prepared to make your own decisions about this is to know the scientific principles that have already been determined about dieting, weight loss and keep the weight off.

Is it better to be on a high protein diet or a low fat diet, or a low carbohydrate diet?

Calories in food are derived from protein, carbohydrate and fat. We have heard of many different combinations such as:

  • low fat for heart problems and reducing cholesterol,
  • low carbohydrate for diabetes or prediabetes,
  • low glycemic (simple sugars or carbohydrates) *
  • high protein
  • just well-balanced for weight loss

We still think that the amount of weight loss just depends upon the amount of calories eaten and not the mix of fat. protein and carbohydrate. But some diets are easier to stick to than others. And many times there are claims that one type of diet or the other promote weight loss faster.

As it turns out, several studies have shown that low carbohydrate diets tend to out perform other diets as far as producing more weight loss in the same amount of time. If a person is on a low fat diet in which the percent of fats are held constant, eating more protein and less carbohydrates results in a greater percentage who lost more than 22 lbs (10 kg).

One study in obese children demonstrated that a low glycemic diet was more effective in reducing weight than a low fat diet. Not all studies show a greater weight loss from a low carbohydrate diet but it does improve glucose, insulin and cholesterol levels in contrast to a higher carbohydrate diet (1). Low fat, vegetarian diets will also significantly lower serum cholesterol and if you hold calories and protein constant and just vary the fat percentage from 10 to 40%, there is no difference in weight loss.

[ed note - I favor a low glycemic diet for women who are premenopausal or taking progesterone/progestins because they may promote insulin resistance and women find they cannot lose weight in spite of being calorie restricted. The book "Sugarbusters" is highly recommended.]

How much calorie restriction is needed to lose weight?

There is no reason, and it is probably somewhat dangerous, to restrict your daily calories below 800 kcal/day. Most low calorie diets tested in the literature for women range from about 1000-1500 kcal per day (approximately 12 to 15 kcal/kg body weight) . At this rate, average weight loss approximates about 1.5 - 2 lbs/week which is about the rate achieved by the well-balanced diet of the Weight Watchers® program.

A pound of fat has approximately 3500 kcal of energy. A deficit of 1000 kcal per day should result in about 7000 kcal/week deficit or two lbs (2 kg) of weight lost per week. If you are sedentary with an energy expenditure of 1800 kcal per day, you will be much more restricted in what you may eat than if you are more active at 2200 calories per day.

Do diet pills work?

Diet supplements may be prescription or non prescription. They may claim to speed up metabolism, produce a loss of appetite, inhibit absorption from the gastrointestinal tract or in some other way alter the metabolism of food into energy. The claims may be true or false.

Successful prescription pharmaceutical supplements include:

orlistat (Xenical®)
sibutramine (Meridia ®)
fluoxetine (Prozac®)
dexfenfluramine (Redux ®),
Leptin, a protein hormone to regulate body weight
and ephedrine and caffeine .

Imipramine, a mild, generic antidepressant may also be a useful adjuvant for a person who is a binge eater. All of the diet pills have side effects, however, and they must be taken under a physician's supervision.

You may remember the regimen called fen-phen (fenfluramine Pondimin® and phentermine Fastin®, Adipex P ®) that has been taken off the market because long term use has been associated with heart problems. Used for 3 months or less, those products are thought to be safe but the long term use created the serious problems. All of the above prescription diet pills are only useful in the short term to get a weight reduction diet started. They should not be continued beyond 2-4 months without a doctor's supervision.

Non prescription medications and herbal supplements also go through trendy popularity. Some of them have been tested scientifically; most have not. Chitosan is a supplement fiber made from the exoskeletons of shellfish that is supposed to block the absorption of food. It has been shown not to be effective. Hydroxycitric acid, the active ingredient in the herbal compound Garcinia cambogia is another trendy supplement shown not to be effective.

Another non prescription compound heavily promoted for dieting was a fiber supplement, guar gum. Studies have shown this hydrolyzed guar gum fiber supplement does not help produce satiety, a feeling of a full stomach, as advertised. There have even been serious complications described from use of guar gum ( in a product Cal-Ban 3000 ®) including esophageal and small bowel obstruction. This event illustrates very well why it is not a good idea to use unknown, untested products claiming to aid in weight loss.

An as yet unanswered question is whether any of the dietary supplements, prescription or non prescription allow you to lose weight quicker on the same amount of calories without taking the supplement, or whether the purpose of the supplement is merely to increase one's motivation to start a diet or continue complying with the diet more strictly and longer than someone not taking a supplement.

It is interesting that diet studies using supplements do not seem to show more weight loss than diets just advocating a certain protein/fat/carbohydrate mixture or a specific calorie counting level. Sticking to the diet after the first few weeks when motivation is higher seems to be the key.

When one group of investigators compared a traditional calorie counting diet with two other very simple plan diets, milk only and milk only plus one designated food, they found that the "simpleness" of the study diets resulted in as much weight loss as diets using prescription medications.

The moral of this story is that any simple plan type of diet can result in significant weight loss whether that diet is rice only, chicken and rice, grapefruit and eggs, cabbage soup, milk only, or milk and cereal. It is probably not the dietary supplement that produces any weight loss but only that it keeps the plan simple and improves compliance with the calorie restriction of the diet plan.

What is the role of exercise in relation to weight loss?

You would think that there would be no question as to whether exercise should be included as part of weight reduction diet program. Everyone advocates it and reminds us that exercise not only burns fat but will speed up body metabolism for several hours afterwards.

The scientific data, however, does not favor that exercise produces much weight loss at all, at least not in any proportion to what diet produces. One study comparing 3 groups of obese women on diet alone, diet plus aerobic exercise and diet plus strength training found no differences in weight loss across the 3 groups. The mean weight loss was about 30 lbs (14 kg) over 16 weeks following a 925 calorie daily diet.

The exercise groups did not lose more weight even though they were on the same calorie restricted diet. Another investigation found no difference in weight loss between diet only and exercise induced weight loss with diet restriction but there was a slightly greater body fat loss in the exercise group.

One might argue that the amount of exercise is not enough in these studies to burn that many calories. In a non diet study conducted over 18 months that compared continuous exercise at 60-75% of maximum aerobic capacity, 3 days per week, 30 minutes per session, versus exercise intermittently using brisk walking for two, 15 minute sessions, 5 days per week, it was found that the more intensive aerobic exercise program resulted in a weight loss of 2.6% of pre study body weight compared with 0% change in the milder exercise, walker group.

Thus one should conclude that while exercise may be good for other reasons, weight loss is not its primary benefit. Even blood pressure may not be lowered with weight loss. In fact making permanent lifestyle changes such as using stairs more often or spending less time in a sitting position, may be more effective than an aerobics program in keeping weight off because it is more likely to represent a regular habit.

What is the long term success of weight loss programs, i.e., can the weight be kept off?

With most diet programs, over 50% of people regain the lost weight within one year, 75-80% regain the weight within 2-3 years and less than 5% keep the weight off permanently. Satisfaction with body image may play a role.

At least one study indicates that those who were unhappy with their body image or who had previously been on unsuccessful weight loss programs were more likely to regain their weight sooner. Since keeping weight off is the main challenge; a successful weight loss program should include some sort of long term behavioral modification.

While exercise does not compete very favorably with diet alone for weight loss, studies do show that exercise helps keep the weight off longer. Even a simple walking program instituted after the main weight loss program ends is effective in keeping weight regain lower after 2 years of follow up.

Again, it may not be the exercise producing the weight loss maintenance but rather it provides the continued motivation to remain on a reasonable diet. We suspect this because if a continued medication is used such as orlistat (Xenical®), there is as much blunting of weight regain as with a walking exercise program.

Are there any adverse effects from dieting that I should know about?

We always worry that dieting can cause a deficiency of vitamins or a danger of excess aspartame (NutraSweet®) from diet foods. We are cautioned to drink excess water to prevent kidney disease or stones. But what does the data show?

Here are some principles found in the medical literature:

  • weight loss in postmenopausal women decreases bone mineral density 
  • high protein diets at 25% energy from protein (not super high) may increase kidney size but they do not have adverse kidney function affect 
  • a very low calorie (520 kcal/day), low fat (2 gm fat/day) rapid weight loss diet can cause cholesterol gall stones - some dietary fat (30 gm /day) is needed to promote gallbladder emptying.
  • a reduced fat diet does not increase need for micronutrients such as vitamin A and E 
  • diet containing aspartame actually results in more weight loss and loss maintenance 
  • weight loss of 1 lb/week (0.5 kg) on 500 kcal less than normal intake during lactation does not affect the height and weight growth of the newborn infants 
  • dieting does not cause the new occurrence of eating disorders such as binge eating, bulimia 
  • diet produces a decrease in the tonic LH levels and insulin levels that are elevated in obese (PCOS) infertility patients 

In summary, It really is the calorie restriction that produces weight loss. Pills or diet programs or regimens will help promote weight loss by increasing the motivation of a woman to continue to diet. In order to keep weight off permanently, there has to be a long term change in a person's daily living and eating habits.

Regular mild exercise of only walking for 15 minutes several times a week is a very useful habit that can promote permanent weight loss.

If you have trouble getting started on a diet program, any special diet or group of supplements will likely help as long as you:

  1. investigate the components to make sure they have been tested to be safe
  2. can afford the monetary cost of the program
  3. do not delude yourself into thinking that you can eat as many calories as you have been eating or want to eat and still lose weight

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