A recent study found that people on high fat diets gain less weight than people on high protein diets with equivalent calorie content — but low-protein eaters store more than 90 percent of their weight as fat.
Which way is the pendulum swinging now? Sometimes, low-fat diets are all the rage; at other points, dieters are busy eliminating all traces of carbohydrates from their plates. Everyone has a story about someone who lost tons of weight on this or that particular diet, and sometimes it’s difficult to know what is true when it comes to these “successes.”
That’s why scientists at Pennington Biomedical Research Center in Baton Rouge, Louisiana, set about studying dietary intake and what kinds of foods cause greater weight gain. The results show that it’s not only the amount of calories you eat but also what type that influence your weight the most.1 Hardly surprising, until you look a bit more closely at the data.
The 25 normal-weight adults participating in the study were put on a high-calorie eating plan. They all consumed 954 extra calories each day for eight weeks, which is approximately 40 percent more calories than the average person should be eating. Although the calorie counts were the same, the volunteers were randomly told to follow one of three diets that differed based on the percentage of fat and protein offered; only carbohydrates were kept constant. (And we could go into a long discussion about why that decision may have rendered the study less than completely useful.) In any case, the low-protein diet was 6 percent protein, 52 percent fat, and 42 percent carbs. The normal-protein diet (closest to the typical American’s eating habits) was 15 percent protein, 44 percent fat, and 41 percent carbs. The high-protein diet was 26 percent protein, 33 percent fat, and 41 percent carbs.
All of the participants gained weight during the trial — not exactly a shock considering the number of calories they were taking in. But surprisingly, those with the low-protein, higher-fat ratio gained about half the amount that those on the other two regimens did, which flies in the face of conventional diet wisdom that high protein diets are the secret to weight loss. The low-protein group gained an average of 7 pounds over the eight-week study, while the other two groups averaged a 13 to 14 pound gain.
However, and this is a big however, the low-protein eaters stored more than 90 percent of the excess calories they ate as fat, and they lost lean body mass. So they may not have gained as much weight, but their bodies started breaking down their own muscle stores when not enough protein was consumed. In contrast, those who ate an average or above average amount of protein did not lose muscle mass and, while they may have gained more weight, only 50 percent of those extra calories were stored as fat.
What it comes down to is that diets higher in protein, at least up to a point, help build muscle tissue, which keeps the metabolism revved up and makes it easier to burn calories. Those with too little protein in their diets lose muscle, which makes the metabolism sluggish and ultimately results in difficulty burning even a normal amount of calories. And, when we consume greater quantities of protein, we tend to stay full longer, because it is more satisfying and takes longer for our bodies to break down than fats and simple carbohydrates.
That does not mean, though, that the extreme high-protein diets that so many people swear by are good for you. It depends on several factors. One factor is the source of the protein. If you are getting the vast majority of your calories from steak, bunless burgers, and bacon, you may lose some weight from going practically carb-free, but you are putting yourself at risk for developing heart disease and cancer. A 2010 study at Simmons College in Boston followed 85,000 women aged 34 to 59 and 45,000 men aged 40 to 75.2 It showed that over a period of 20 years, adherents to a low-carb diet were 12 percent more likely to die than those who ate a higher-carb diet. Plus, among the low-carb dieters, those who got their protein and fat from animal sources (red and processed meats) were 14 percent more likely to die of heart disease and 28 percent more likely to die of cancer than those who ate a higher-carb diet. In contrast, low-carb dieters who got their protein and fat from vegetable sources such as beans and nuts were 20 percent less likely to die than those eating a higher-carb diet.
Which brings us to the second factor — what sources of protein and fat are you consuming, and how are you cooking your food.
- Meat that is not laced with antibiotics and growth hormones will not have the same health consequences as organic meat.
- Grassfed meat will not lead to the same heart disease as corn fed because of its superior omega-6:omega-3 ratio.
- Low temperature cooking or raw is healthier than high temperature grilling — and marinades help nullify the negative health effects.
- Many of the same rules apply to chicken.
- And as for fish, is it farm raised or wild caught? Is it low mercury or high mercury? Is it omega-3 rich?
- Are your fats high omega-6 or omega-3? Are you using healthy fats like coconut oil or unhealthy highly refined corn or safflower oils?
- Are your carbs (even if reduced in amount) complex, unprocessed whole vegetables and fruits, or high glyemic, high sugar?
Ultimately, you need to consider not only your overall intake of protein, but whether it’s from a healthy source. And the same goes for your fats and carbs. Keep in mind, too, that moderation is a good thing. An occasional treat of any kind won’t hurt if most of the time you are eating nutritiously.
1 Song, Sora. “It’s the Calories, Stupid: Weight Gain Depends on How Much–Not What–You Eat.” Time Healthland. 4 January 2012. Accessed 23 February 2012. <http://healthland.time.com/2012/01/04/low-protein-diets-lower-weight-but-dont-cut-fat/>.
2 Fung, Teresa T.; van Dam, Rob M.; Hankinson, Susan E.; et al. “Low-Carbohydrate Diets and All-Cause and Cause-Specific Mortality.” Annals of Intenal Medicine. 7 September 2010. Accessed 23 February 2012. <http://www.annals.org/content/153/5/289.abstract?sid=a98e8b66-4fa9-47c0-80f9-8f69a4dcc7cb>.