Going low-carb? Pick the right proteins

Low-carb eating plans like the Atkins diet were once so popular that they graced the covers of Newsweek and other magazines. Some experts championed these diets as the best way to lose weight. Others scorned them as the heart-clogging way that might help you shed pounds but put your health at risk. Now several large randomized controlled trials — the gold standard of medical research — have shown that low-carb diets are as good as low-fat diets for losing weight, and may even be better. But how do they fare for long-term health?

Most low-carb diets deliver more protein and fat than "regular" or low-fat diets. We know there are good and not-so-good fats and carbohydrates. Could the same hold true for protein sources? If so, then the type of protein that dominates a diet can influence health as much as the kinds and amounts of carbohydrates or fats.

The evidence

Researchers at the Harvard School of Public Health have been following 85,000 female nurses and 45,000 male health professionals since the mid-1980s. Every few years, the participants fill out questionnaires detailing what they eat and provide other information on their health. This wealth of data is offering some insight into the long-term effects of different low-carb diets.

In one study, the researchers created scores for each nurse's intake of protein from red meat, poultry, fish, dairy, eggs, nuts, and beans. The findings:

  • The more protein from red meat, the higher the chances of developing heart disease.
  • Women who averaged two or more servings of red meat a day had a 30% higher risk of developing heart disease than those who had one or fewer servings a day.
  • Replacing one serving of meat with one of nuts reduced the risk by 30%.

In a separate study, the researchers created scores that reflected both the amount of carbohydrate in the diet and the main sources of protein. Among the nurses and male health professionals, those with a low-carb diet heavy in animal protein were 23% more likely to have died over 20-plus years of follow-up than those with "regular" diets, while those following a low-carb diet rich in plant protein were 20% less likely to have died.

Protein sources

Good sources of protein deliver different amounts of saturated fats, carbohydrates, and fiber. Here's what 3 ounces of different protein sources contain.

Food

Calories

Protein (g)

Carbohydrate (g)

Saturated fat (g)

Roasted chicken, white meat

130

23.1

0

0.9

Roasted leg of lamb

184

22.7

0

3.9

Cooked ground beef (85% lean)

197

20.9

0

4.5

Baked coho salmon

151

20.7

0

1.7

Roasted chicken, dark meat

151

19.8

0

2.1

Baked ham

151

19.2

0

2.7

Boiled green soybeans

127

11.1

10

0.7

Cottage cheese, 1% milk fat

61

10.5

2.3

0.6

Boiled black beans

114

7.6

20

0.1

Source: USDA National Nutrient Database

Putting it all together

To your body, protein from pork chops looks and acts the same as protein from peanuts. What's different is the protein "package" — the fats, carbohydrates, vitamins, minerals, and other nutrients that invariably come along with protein. The two Harvard studies add to a growing body of evidence that emphasizing plant protein sources is a better bet for long-term health.

If you are overweight, shedding pounds can improve everything from your blood pressure to the way you feel. Do it the wrong way, though, and shrinking your waistline could also shrink the number of birthdays you get to celebrate. Instead of having bacon and eggs for breakfast, a burger for lunch, and steak for dinner, getting more of your protein from plants may help you steer clear of heart disease and live longer.

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