In the world of diet and nutrition, there’s always a new way to lose weight.
The latest strategy, backed by the likes of Pippa Middleton and Adele, was outlined in detail earlier this year in a book called the SirtFood Diet, which provides a nutrition plan built on foods like kale, green tea, dark chocolate, wine, blueberries, olive oil, soy, and other foods high in specific plant compounds that stimulate proteins called sirtuins.
“Sirtuins are a class of proteins found in living things”—including humans—“that research has shown to be involved in important biological processes such as aging, cellular death, inflammation, and metabolism,” says Stacy Sims, Ph.D., a sports nutrition expert and senior research fellow at the Adams Centre for High Performance at the University of Waikato in New Zealand.
In other words, sirtuins might help you live longer, and according to their proponents, they may also help you shed body fat. The hope is that eating a ton of sirtfoods will stimulate the sirtuin genes (sometimes called skinny genes) in a similar fashion to fasting.
But does it really work that way? First, some background: In mammals, there are seven types of sirtuins, which range from SIRT1 to SIRT7. Of them, SIRT1 is the one that researchers are most interested in, says Sims. “SIRT1 is sometimes referred to as the ‘guardian’ against oxidative stress and DNA damage.”
The idea of the Sirtfood Diet is if you can activate SIRT1, you can produce more mitochondria, the powerhouse of the cells, which will help reduce oxidative stress, allowing you to age slower, says Mike Roussell, Ph.D., a nutritional consultant in Philadelphia.
The problem? “You can’t possibly consume enough of the foods recommended by this diet to increase sirtuins,” says Roussell. Take red wine, which is included in the SirtFood Diet: “To get 20 milligrams of resveratrol [an antioxidant that stimulates SIRT1], you would need to drink more than 40 glasses of wine,” Roussell says. Which, to be clear, we aren’t suggesting you do.
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Also, research from Endocrine Journal finds that SIRT1 regulates appetite differently from person to person. “So for some people, increased SIRT1 expression might make you hungry,” says Roussell.
Now, the fact that people lose weight by following the SirtFood Diet likely comes down to two factors:
- The foods in the plan tend to be rich in nutrients.
- The book requires a week of intense calorie restriction—just 1,000 calories a day for the first three days and 1,500 a day for the rest of the week. And most of those calories are from juice.
Restricting calories, as you probably know, is the most reliable strategy for losing weight. And for what it’s worth, research from Finland’s Helsinki University found that low-calorie diets may naturally increase sirtuin activity, regardless of whether you’re eating sirtuin-rich foods or not.
So sure, add a few sirtuin foods to your diet: kale, strawberries, walnuts, buckwheat, celery, red onions—all good stuff. But don’t assume that you can’t eat anything else. If you’re serious about losing weight, focus on lean protein, vegetables, and whole grains—and keep your total energy intake down.
You can determine your ideal weight-loss calorie goal by finding your resting metabolic rate (the calculator at My Fitness Pal can help) and then multiplying it by 1.3, says Krista Austin, Ph.D., an exercise physiology and sports nutrition expert. Go any lower than that, and you risk slowing your metabolism down.
“As health fads go, there’s very little to say against sirtfoods,” concludes Sims. “However, these are simply one facet of a healthy diet. No one needs to buy a sirtfood cookbook.”
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