The best fat-burning foods
By Susan M. Kleiner, PhD, RD, FACN, CNS, FISSN
(this article was originally published in February of 2009)
A decade ago, it would have been hard to write this column. While there were all kinds of foods and supplements sold with promises to burn fat, none of them had any scientific data to support the claims. Today, scientists are beginning to understand how certain foods actually do rev up metabolism or enhance hormones to help us burn fat. You’ll read about the six best fat-burning foods below. Ten years from now, a column on fat-burning foods is bound to be full of science-based information on dozens of foods that can help boost metabolism and burn fat. So stay tuned.
PROTEIN
In addition to helping build muscle, your metabolic furnace for burning fats, lean protein helps stoke the fat-burning fires— its thermogenic effect is 20 to 30 percent compared with an anemic 3 to 12 percent for carbohydrates. This basically means that it takes many more calories to digest, absorb and utilize protein versus carbohydrates. As you include protein in every meal and snack all day long, you raise your fat-burning potential, as well.
Make sure to choose lean protein sources such as eggs, chicken, turkey, fish, lean red meat and vegetable proteins. If you don’t already have a blender and some protein powder, buy them. When you crave a high-fat or high-carb snack, reach for a protein shake instead.
FISH
For many years, nutritionists assumed you lost weight when you ate fish because it has fewer calories, pound-for-pound, than red meat. Now however, it appears that reasons go above and beyond calories. Most important, the type of fat found in fish appears to enhance the efficiency of the hormone leptin. This protein circulates in your bloodstream and, like the hormone insulin, is a key hormone in the weight-management equation. Leptin regulates your food intake as well as your body’s energy expenditure. When cells in your brain sense a rise in leptin, they signal other parts of your nervous system to turn down your appetite and turn up your metabolism.
I recommend that all my clients eat five fish meals a week. The omega-3 fats support a healthy heart, a healthy brain and nervous system, and possibly enhance the efficiency of leptin, helping you boost your metabolism and control appetite. It hardly gets better than this. While all fish have more omega-3 fats than a hot dog, the fatty fish like salmon, black cod, herring, sardines, mackerel, halibut, fresh tuna and shellfish are highest in omega-3 fats.
OLIVE OIL
The kinds of fat that you eat can influence your energy expenditure and bodyweight. Energy is released through heat production in a process called nonshivering thermogenesis, which is controlled by uncoupling proteins (UCP) in the cells of brown fat, white fat and muscle. Researchers interested in finding out if diet can influence this process investigated possible dietary enhancements of thermogenesis in rats. They found that olive oil, which is high in monounsaturated fats, increased the activity of the UCPs, and hence of metabolic rates. Because of the short duration of the study, published in the American Journal of Clinical Nutrition, no differences in bodyweight were recorded between the rats fed olive oil and those fed other fats. However, international studies have shown that Mediterranean-style diets higher in olive oil are associated with weight maintenance and little weight gain over time compared with diets lower in olive oil. However, overall fat consumption still does add many calories to the diet, and those subjects with a very high fat consumption were overweight compared to those who controlled their total fat intake.
GREEN TEA
Certain natural chemicals called catechins are abundant in green tea; animal and human studies show that these chemicals appear to increase fat burning and stimulate thermogenesis, and the combination with caffeine in tea appears to boost the effect. The amount that you need to consume isn’t absolutely clear. A 1999 study in Maryland used six, one-quarter cups of tea per day for four days. A more recent Japanese study found successful results feeding two one-half cups every day for 12 weeks. A study from the UK published this year demonstrated increased fat burning in exercising young men. In this study, researchers used a green tea extract of three capsules (containing a total of 890 +/- 13mg polyphenols and 366 +/- 5mg EGCG [the catechins]). Since the amount of catechins is difficult to control with brewing, many practitioners recommend using a green tea extract for better dose control.
MILK
Milk ranks high on the list of fat-burning foods. No doubt you’ve read about or heard the commercials for how milk can help you lose weight. The high calcium content of milk helps it turn off a key obesity gene, keeping your body from turning up the fat-making machinery to high, and helping your fat-burning metabolism run smoothly. At the same time milk is the primary source of whey protein, shown in studies to enhance fat burning and limit the turnover of calories into fat storage by the liver. Subjects on a calorie-reduced diet given 20 grams of whey protein supplement every day after an exercise bout lost significantly more fat and maintained significantly more muscle mass compared to subjects given a placebo. Milk is a natural source of whey protein, and you will also benefit from adding a whey protein supplement to your diet.
CHILI PEPPERS
Studies have shown a thermogenic effect of capsaicin, a compound found in chili peppers. When chili-containing meals have been fed to subjects regularly for four weeks, results have shown an attenuation of high blood insulin levels after the meals. While weight loss was not studied, a lowering of blood insulin levels in overweight subjects may ultimately lead to weight loss. Other studies using a capsaicin supplement have been shown to be effective, but the dosage must be strictly followed. One Danish study using a supplement combining green tea extract, capsaicin, tyrosine and calcium for seven days showed a 2 percent increase in energy expenditure in overweight and obese men. The researchers found that only the capsules that were not enterocoated were effective. The coating, which inhibits digestion in the stomach, inactivated the efficacy of capsaicin.
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