Developed by two UK-based men with master’s degrees in nutritional medicine, the diet has become very popular among celebrities and athletes across the pond. Both Pippa Middleton and Adele are rumored to have followed this plan. Like many other diets, the Sirtfood Diet touts effective and sustained weight loss, incredible energy and glowing health. But is the Sirtfood Diet another diet fad, or is there any truth to its claims?

What Is the Sirtfood Diet?

The plan claims that eating certain foods will activate your “skinny gene” pathway and have you losing seven pounds in seven days. The theory behind this diet is that foods like kale, dark chocolate and wine contain a natural chemical called polyphenols that allegedly turn on genes that mimic the effects of exercise and fasting (and ultimately lead to weight loss). Strawberries, red onions, cinnamon and turmeric are also powerful sirtfoods. These foods will trigger sirtuins, which are proteins that some research has linked to regulating inflammation and burning fat. The science sounds enticing, but in reality there’s not much research to back up these claims. Plus, the promised rate of weight loss in the first week is rather quick and not in line with the National Institute of Health safe weight loss guidelines of one to two pounds per week.

The diet has two phases:

• Phase 1 last for seven days. For the first three days, you drink three sirtfood homemade green juices and one meal rich in sirtfoods for a total of 1,000 calories. On days four through seven, you drink two green juices and two meals for a total of 1,500 calories.
• Phase 2 is a 14-day maintenance plan, although it is designed for your to lose weight steadily (not maintain your current weight). Each day consists of three balanced sirtfood meals and one green juice.

After these three weeks, you’re encouraged to continue eating a diet rich in sirtfoods and drinking a green juice daily. You can find several sirtfood cookbooks online and recipes on the sirtfood website. One green juice recipe found on the sirtfood website consists of a combo of kale and other leafy greens, parsley, celery, green apple, ginger, lemon juice and matcha. Buckwheat and lovage are also ingredients that are recommended for use in your green juice. They diet recommends that juices should be made in a juicer, not a blender, so it tastes better.

A day on the Sirtfood Diet might look like this:

• Breakfast: Soy yogurt with mixed berries, chopped walnuts and dark chocolate
• Lunch: A sirtfood salad made with kale, parsley, celery, apple, walnuts topped with olive oil mixed with lemon juice and ginger.
• Dinner: Stir-fried prawns with kale and buckwheat noodles.
• Plus one sirtfood green juice per day.

Things to Consider Before Trying the Sirtfood Diet

According to the International Food Information Council Foundation (IFIC), this diet focuses only on weight loss. Certainly weight is a determinant of health, but it is not the only one. Further, weight loss can be due to the calorie restriction when following this plan.

The diet itself cuts out numerous food groups and is limiting. When you cut or limit food groups in any diet, it means that you’re also limiting the nutrients that your body gets. Dairy foods, which provide an array of essential nutrients including several that most folks lack, aren’t recommended on the plan. In addition, cutting out numerous foods can damage your relationship with food and lead to disordered eating. Further, the polyphenol-rich food matcha often contains lead in the tea leaves which is potentially dangerous to your health especially when taken regularly.

When on the Sirtfood Diet there are numerous seasonal ingredients that are needed in order to properly follow this diet. This means that foods like strawberries and kale may be tough to get certain times of the year. The diet is also tough to follow when traveling, at social events and feeding a family with young kids. You’ll also need to invest in a decent juicer, which can cost you a minimum of $100. Besides the free recipes available on the website, you may need to invest in some of The Sirtfood Diet cookbooks.

Bottom Line

Polyphenol-rich foods can certainly be included in a weight loss plan, but they aren’t the basis for an entire diet. You most certainly don’t need wine and dark chocolate every day, plus too much matcha is potentially dangerous.

Toby Amidor, MS, RD, CDN, is a registered dietitian and consultant who specializes in food safety and culinary nutrition. She is the author of The Greek Yogurt Kitchen: More Than 130 Delicious, Healthy Recipes for Every Meal of the Day .

*This article was written and/or reviewed by an independent registered dietitian nutritionist.

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