Despite what you may have heard, some diet pills can help you drop pounds safely. I’ve spent much of my career investigating nutritional supplements to aid weight loss. Here are three that I have found to be quite effective. Try one or all three, but always check with your doctor before taking any supplement.


I started conducting scientific research on garcinia cambogia and its active ingredient hydroxycitric acid (HCA) in 2003 and wrote about it in my book The Natural Fat-Loss Pharmacy in 2007. But this weight-loss supplement didn’t really become popular until 2012, when Dr. Oz touted it.

Garcinia cambogia is the botanical name for the Malabar tamarind, a ­variety of the tamarind fruit. (Tamarind, a delightfully sour spice popular in the cuisine of India, is derived from the dried rind of the fruit.) Scientific analysis of the Malabar tamarind in the 1960s and ’70s showed that it is a rich source of HCA—a unique compound that lowers levels of ATP-citrate lyase, an enzyme that helps the body turn carbohydrates into fat. In other words, an extract of garcinia cambogia can help to reduce your body’s production of fat.

Since that time, my research and the research of other scientists have confirmed that HCA can help people shed pounds. In one study designed to produce 100% compliance with the protocol, people taking HCA lost 12 pounds over two months, while those taking a placebo lost only three pounds. In a subsequent and similar study, HCA-takers lost 10 pounds, while placebo-takers lost 3.5. What to look for…

The right form. HCA comes in two forms – “free” HCA, which is active in the body but tends to be unstable and to exhibit poor absorbability, and a more stable but inactive form, HCA “lactone.” Formulating active HCA with certain minerals, such as potassium, magnesium and/or calcium, to create a “salt” makes the compound stable and improves absorption. The better HCA products are mixtures, such as potassium-magnesium or potassium-calcium HCA salts. For effectiveness, you also need a garcinia cambogia extract that is at least 50% HCA, with the maximum level being approximately 70%. This is why, when I have studied HCA, I mostly have used an active, stable form called HCA-SX (Super CitriMax, which includes both potassium and calcium and is 60% HCA). More recently, I studied a potassium-magnesium form of HCA with good outcomes.

Editor’s note: The potassium-magnesium HCA salt that Dr. Preuss studied can be found in HCActive from Jarrow Formulas. The HCA-SX potassium-calcium HCA salt that he studied is an ingredient in several garcinia cambogia products, including those from Genesis Today, NutriGold, NutraCentials and Pure Health.

The right dose. Studies show that the best single dose of the products currently on the market is 1,500 milligrams (less might not work).

The right time. Take it three times a day, 30 to 60 minutes before breakfast, lunch and dinner, on an empty stomach. If you take HCA with food, it is poorly absorbed.

Realistic expectations. The scale may not register any weight loss for two weeks or so because accumulation of water and glycogen (the form in which glucose is stored in the tissues) counteracts the fat weight loss.

Caution: People who are diabetic…taking a statin to lower cholesterol…or suffering from dementia should consult with their physician prior to taking this ­supplement.


If you’re a typical American, a significant percentage of your calories are from refined carbohydrates such as sugar and white flour—calories that your body can easily store as fat. Cutting back on refined carbs is the best course of action, but that can be hard for some people because they are addicted to them. (Like other addictive substances, refined carbs stimulate the brain’s pleasure centers.) To deal with carb overdosing, I recommend taking a carbohydrate absorption blocker, or carb blocker.

Made from an extract of white kidney beans (Phaseolus vulgaris), the supplement works by blocking the action of alpha amylase, a digestive enzyme secreted by the pancreas that breaks down carbs in the small intestine. Research shows that taking a carb ­blocker can cut carbohydrate absorption by 60% to 70%—in other words, taking a carb blocker and then eating two cups of pasta would be like eating only two-thirds of a cup.

There have been dozens of studies on carb blockers. In a study that I coauthored, dieters taking a carb blocker lost 6.5 pounds over one month, while those taking a placebo lost one pound. Carb blockers mainly work on starchy foods, such as bread, cake, cookies, chips, pasta, rice and potatoes. I personally reserve carb blockers for meals heavy in carbohydrates such as those at Italian restaurants.

Suggested dosage: The typical dose is 1,000 milligrams per meal.

Time of intake. Take it 15 minutes before a high-carbohydrate meal. If you don’t like swallowing a large pill, you can open the capsule and sprinkle the (tasteless) carb blocker on your meal.

Best products. Most of the studies on carb blockers and weight loss have been conducted using Phase 2 carbohydrate inhibitor from ­Pharmachem. (The FDA has approved this claim for Phase 2: “May assist in weight control when used in conjunction with a sensible diet and exercise program.”) Supplements with Phase 2 include: Carb-Intercept with Phase 2 from ­Natrol…Phase 2 Carb Controller from Swanson…and Phase 2 Starch Neutralizer from Now.

Carb blockers can cause gastrointestinal cramps and gas, but this is rare.


When levels of this mineral are low, the hormone insulin does a poor job of moving blood sugar out of the bloodstream. Doctors reasoned that supplying the body with more chromium might burn up more blood sugar so that less is stored as fat. But many study results have been disappointing. In a recent review of 11 studies on chromium and weight loss published in Obesity Reviews, dieters who took chromium lost an average of only 1.2 pounds more than placebo-takers. So why am I recommending the nutrient?

Important scientific evidence: In 1999, I published a study in Diabetes, Obesity and Metabolism on 20 overweight women who were restricting calories and exercising regularly. For two months, the women took a placebo. In another two-month period, they took 600 micrograms (mcg) of chromium daily. They lost the same amount of weight on the supplement and the placebo. But…

When they took the placebo, they lost 92% of their weight as muscle and 8% as fat. When they took chromium, they lost 84% as fat and 16% as muscle. That is a crucial difference.

Pound for pound, muscle burns 60% more calories than fat. When you lose muscle during weight loss, you gain your weight back…as fat! And because you now have a fatter body, you’re likely to gain back even more weight than you lost. That’s exactly what happens to 90% of people who lose weight—they shed the pounds only to gain them back again (and then some). Chromium can help you not only firm your body during weight loss but also stop or at least reduce weight regain.

Suggested dosage: 200 mcg, three times a day, while dieting. After you’ve reached your weight-loss goal, switch to 200 mcg once a day. I have taken chromium daily for at least 15 years.

It is best to take chromium separately from meals and other supplements, which can interfere with its absorption.