Coconut Oil: Diet Miracle or Fad?
Some people promote coconut oil as a healthy addition to a weight-loss diet, even though it has higher levels of saturated fat.
Reviewed By Brunilda Nazario
Is it possible to add fat to your diet and lose weight? Yes, if it's the right fat, says naturopath Bruce Fife, ND, author of Eat Fat Look Thin. He recommends adding coconut oil and substituting it for polyunsaturated oils to suppress appetite, boost metabolism, and bring about weight loss.
"Lots of people have reported that when they add coconut oil to their diet, it was enough to promote weight loss," says Fife. "Some people don't notice a drop in weight, which often means they're simply eating too much. Calories are important." His own experience with coconut oil produced a gradual weight loss over six months of about 20 pounds, which he'd been unable to lose previously through diet and exercise.
He advises using about three tablespoons of natural coconut oil, either virgin or processed, daily. His patients use it in place of polyunsaturated fats for stir-frying and salad dressings, add it to other foods, or take it straight. The fat is also present in canned coconut milk (not the liquid inside the coconut), which can be substituted for milk in many recipes, and fresh coconut fruit, which can be eaten as a snack or grated over fruits and salads.
How Does Coconut Oil Promote Weight Loss?
"I think the real key to coconut oil and weight loss is the fact that it decreases your appetite while you're eating the meal and afterwards," says Fife. "Studies show that when these fats are added, people are satisfied sooner and eat less, and at the next meal they don't make up for it by eating more."
Coconut oil is a medium-chain triglyceride (MCT) while most other fats, such as vegetable oils and animal fat, are long-chain triglycerides (LCTs). "The length of the molecule determines how the fat is metabolized," says Fife. MCTs are rapidly broken down, and the body burns them much like carbohydrates for energy. LCTs, however, are deposited in fat cells. "With MCTs, you're eating fat calories, but you're eating fewer effective calories because metabolism rises, and you end up burning the calories, not storing them as fat. You can eat much more coconut oil than other fats before your body will convert it into fat."
Fife says that the types of oils present in coconut oil stimulate metabolism. "It promotes thermogenesis [burning of calories to produce heat], and some people with low thyroid function tell me they feel warm and their body temperature rises one or two degrees after eating coconut oil." People with low thyroid function have a low metabolism and can have a decreased ability to lose weight.
Can a Saturated Fat Be Good for You?
Coconut oil is highly saturated fat, which puts it in a class with animal fat. It's the oil banned from theater popcorn and denounced by the Center for Science in the Public Interest (CSPI). Foods found to contain coconut oil and other highly saturated fats end up in the CSPI newsletter's "Food Porn" category.
Six years ago, Fife says he would have agreed that all saturated fats raise serum cholesterol and cause heart disease. He advocated a low-fat diet for his patients trying to lose weight. A colleague piqued his interest in coconut oil, and he began investigating the health benefits. "Coconut oil is used in IV solutions in hospitals and infant formulas," he says. "I thought, 'If it's so bad, why is it given to sick people and babies?
"MCTs are digested much quicker than LCTs, and by the time they reach the intestinal tract they're completely broken down."
Because they're so easily digested, MCTs in coconut oil are used to provide nourishment to people, such as AIDS patients who have trouble digesting fat. There's further interest in their potential to improve athletic endurance and treat type 2 diabetes.
The limited number of studies on oils similar to that found in coconut (in the form of palm kernel oil, coconut oil, linoleate, and other oils) and weight loss show conflicting results. Two researchers at McGill University in Quebec, Marie-Pierre St.-Onge and Peter J. H. Jones, published a review of the literature in the March 2002 issue of the Journal of Nutrition. Animal trials show that substituting MCTs for LCTs over long periods could produce weight loss. From these preliminary studies they concluded that these types of oils produced an increase in energy expenditure and resulted in a decrease in food intake, suggesting the potential for weight control.
The American Heart Association's Position
Where does the American Heart Association weigh in on coconut oil as an aid to weight loss? "I would be very pessimistic about this, says Robert Eckel, MD, the Association's spokesman on nutrition. He says he's concerned about the effects of high levels of saturated fat. "This is going to be a cholesterol-raising diet."
He says he also doubts claims that coconut oil can boost metabolism. "People have looked in the past as to whether MCTs have thermogenic properties, and I think the answer is pretty well negative. Generally, saturated fats tend not to be as well [metabolized], so if it does have any ability to promote heat generation, it's going to be minimal."
Eckel says coconut oil's effect on metabolism, if any, is modest compared with the potential for raising overall cholesterol and particularly "bad" LDL cholesterol. "Ingesting coconut oil for a short period of time will not do harm, but I'm concerned about the long haul."
"I think coconut oil is promising, but I wish it weren't promoted as 'eat coconut oil and lose weight,'" says Glenn S. Rothfeld, MD, MAc, clinical assistant professor of family medicine at Tufts University School of Medicine in Boston and medical director of WholeHealth New England in Arlington, Mass. He and co-author Deborah S. Romaine wrote Thyroid Balance: Traditional and Alternative Methods for Treating Thyroid Disorders. "The only problem for me is the lack of research." He says most of the studies have been on all the oils and the results are not specific to coconut oil.
He says MCTs have a small and indirect influence on thyroid function, affecting metabolism because they're an efficient fuel. He adds there's some suggestion that MCTs boost the levels of thyroid hormones, which are essential to metabolism, in people with low levels of those hormones. He also advises against taking coconut oil on an empty stomach as it may produce bloating and gas.
Even though three tablespoons of coconut oil represents 360 calories, Rothfeld says those calories needn't concern dieters because they're quickly converted to energy. "Calories aren't all alike," he says, giving an example of two groups in a study who were fed just once a day, one group in the morning and one at night. "They consumed the same 1,200-calorie meals, but the morning group lost weight."
Rothfeld says he doesn't see anything intrinsically bad in coconut oil although he wouldn't recommend it for someone with severe diabetes or a liver condition. "The business about oils has been so confusing," he says. "Thirty years ago, it was found that polyunsaturated oils were great. Now it's found they're not so great. It's fairly certain we eat too many grain-based oils, and olive oil becomes rancid if it's left on the shelf too long. I think it's going to turn out we need a balance of things."
Published Aug. 18, 2003.
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