Harvard Health Blog
Low fat? Low carb? Almost any healthy diet can work for losing weight
Yesterday's nutrition headline was "low-carb, not low-fat, diet linked with increased weight loss." Today it's "no clear winner among popular diets." The diet controversy continues.
For years, low-fat diets were the ones that doctors recommended for weight loss. Experts began to look closer at that advice when the low-carb Atkins and South Beach diets made huge splashes by helping some people lose weight.
Over the past 20 years, diets have been tested in head-to-head trials. Their results continue to illuminate nutrition advice and sometimes frustrate dieters. But there's good news from this important research: almost any diet you stick with will work.
Latest results
Writing in yesterday's Annals of Internal Medicine, a team of researchers reported the results of a randomized, controlled trial conducted at Tulane University Health Sciences Center in New Orleans. One hundred sixty eight overweight men and women without either heart disease or diabetes were randomly assigned to a low-carb diet (less than 40 grams of carbohydrates a day) or a low-fat diet (less than 30% of calories from fat). After 12 months, those on the low-carb diet had lost an average of 12 pounds, compared to 4 pounds in the low-fat group. The low-carb diet also had better effects on protective HDL cholesterol and other cardiovascular risk factors.
Today's Journal of the American Medical Association tells a somewhat different story. A team of mostly Canadian researchers evaluated the results of 48 head-to-head trials of various named diets. These ranged from the low-carb Atkins and South Beach diets to moderates like Weight Watchers and Jenny Craig and low-fat approaches like the Ornish diet. After 12 months, average weight loss with either a low-carb or low-fat diet was the same, about 16 pounds. The researchers also found that the named diets yielded similar weight loss.
One thing that did make a difference was explicit advice to exercise more, or some sort of behavioral counseling along with advice on what to eat.
All healthy diets can be winners
The main message from careful comparisons of different diets is that there's no single diet that's right for everyone. Genes, family, environment, and many other factors determine how much each of us eats. Any healthy diet can help people lose weight. Some respond to one type better than another.
So if you are trying to lose weight, try one you think might work for you. If you give it your best shot and it doesn't work, it's possible that it isn't right for you, your metabolism, taste buds, or situation. Try another.
Also keep in mind that there's more to a diet than weight loss. You could put yourself on a hot dog diet and lose weight. But it wouldn't be good for you in the long run. You need healthful nutrients day in and day out for overall good health. You also need an eating plan you can follow day in and day out that is good for your heart, bones, brain, and every other part of your body.
One eating strategy that can provide all that is the so-called Mediterranean diet. Many studies have linked following this type of diet to longer life and less heart disease, diabetes, cancer, and other chronic conditions.
There are many ways to "eat Mediterranean." The basics include:
- Four or more servings of vegetables a day. A serving is ½ cup of raw or cooked vegetables, 1 cup of raw leafy greens, or ½ cup of vegetable juice.
- Four or more servings of fruit a day. A serving is ½ cup of fresh, frozen, or canned fruit; ¼ cup of dried fruit; one medium-sized piece of fruit; or ½ cup of fruit juice.
- At least 4 tablespoons of olive oil a day.
- One handful (about 1½ ounces) of nuts at least three times a week.
- Three or more servings of beans, peas, lentils, or other legumes a week. A serving is ½ cup.
- Six or more servings of whole grains a day. A serving is 1 cup of dry breakfast cereal; ½ cup of cooked cereal, brown rice, or whole-grain pasta; or one slice of whole-grain or multi-grain bread.
- Three or more servings of fish (especially fatty fish) a week. A serving is 4 ounces.
- One serving of yogurt or cheese a day.
- If you enjoy alcohol, limit yourself to 1 (for women) or 2 (for men) drinks a day. One drink is 5 ounces of wine, 12 ounces of beer, or 1½ ounces of liquor.
At the same time, try not to drink sugar-sweetened soda, juice, or energy drinks. Have sweets, pastries, and commercial bakery goods only as the occasional treat. And go easy on red and processed meats.
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