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Evidence Based

The Sirtfood Diet: An Evidence-Based Review

Trendy new diets seem to pop up regularly, and the Sirtfood Diet is one of the latest.

It has become a favorite of celebrities in Europe and is famous for allowing red wine and chocolate.

Its creators insist that it's not a fad, but rather that “sirtfoods” are the secret to unlocking fat loss and preventing disease.

However, health experts warn that this diet may not live up to the hype and could even be a bad idea.

This article provides an evidence-based review of the Sirtfood Diet and its potential health benefits.

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What Is the Sirtfood Diet?

Woman Drinking Green Juice

Two celebrity nutritionists working for a private gym in the UK developed the Sirtfood Diet.

They advertise the diet as a revolutionary new diet and health plan that works by turning on your “skinny gene.”

This diet is based on research on sirtuins (SIRTs), a group of seven proteins found in the body that has been shown to regulate a variety of functions, including metabolism, inflammation and lifespan ().

Certain natural plant compounds may be able to increase the level of these proteins in the body, and foods containing them have been dubbed “sirtfoods.”

The list of the “top 20 sirtfoods” provided by the Sirtfood Diet includes ():

  • Kale
  • Red wine
  • Strawberries
  • Onions
  • Soy
  • Parsley
  • Extra virgin olive oil
  • Dark chocolate (85% cocoa)
  • Matcha green tea
  • Buckwheat
  • Turmeric
  • Walnuts
  • Arugula (rocket)
  • Bird’s eye chili
  • Lovage
  • Medjool dates
  • Red chicory
  • Blueberries
  • Capers
  • Coffee

The diet combines sirtfoods and calorie restriction, both of which may trigger the body to produce higher levels of sirtuins.

The Sirtfood Diet book includes meal plans and recipes to follow, but there are plenty of other Sirtfood Diet recipe books available.

The diet’s creators claim that following the Sirtfood Diet will lead to rapid weight loss, all while maintaining muscle mass and protecting you from chronic disease.

Once you have completed the diet, you are encouraged to continue including sirtfoods and the diet’s signature green juice into your regular diet.

Summary: The Sirtfood Diet is based on research on sirtuins, a group of proteins that regulate several functions in the body. Certain foods called sirtfoods may cause the body to produce more of these proteins.

How to Follow the Sirtfood Diet

The Sirtfood Diet has two phases that last a total of three weeks. After that, you can continue “sirtifying” your diet by including as many sirtfoods as possible in your meals.

The specific recipes for these two phases are found in The Sirtfood Diet book, which was written by the diet’s creators. You’ll need to purchase it to follow the diet.

The meals are full of sirtfoods but do include other ingredients besides just the “top 20 sirtfoods.”

Most of the ingredients and sirtfoods are easy to find.

However, three of the signature ingredients required for these two phases — matcha green tea powder, lovage and buckwheat — may be expensive or difficult to find.

A big part of the diet is its green juice, which you’ll need to make yourself between one and three times daily. You will need a juicer (a blender will not work) and a kitchen scale, as the ingredients are listed by weight. The recipe is below:

Sirtfood Green Juice

  • 75 grams (2.5 oz) kale
  • 30 grams (1 oz) arugula (rocket)
  • 5 grams parsley
  • 2 celery sticks
  • 1 cm (0.5 in) ginger
  • half a green apple
  • half a lemon
  • half a teaspoon matcha green tea

Juice all ingredients except for the green tea powder and lemon together, and pour them into a glass. Juice the lemon by hand, then stir both the lemon juice and green tea powder into your juice.

Phase One

The first phase lasts seven days and involves calorie restriction and lots of green juice. It is intended to jump-start your weight loss and claimed to help you lose 7 pounds (3.2 kg) in seven days.

During the first three days of phase one, calorie intake is restricted to 1,000 calories. You drink three green juices per day plus one meal. Each day you can choose from recipes in the book, which all involve sirtfoods as a main part of the meal.

Meal examples include miso-glazed tofu, the sirtfood omelet or a shrimp stir-fry with buckwheat noodles.

On days 4–7 of phase one, calorie intake is increased to 1,500. This includes two green juices per day and two more sirtfood-rich meals, which you can choose from the book.

Phase Two

Phase two lasts for two weeks. During this “maintenance” phase, you should continue to steadily lose weight.

There is no specific calorie limit for this phase. Instead, you eat three meals full of sirtfoods and one green juice per day. Again, the meals are chosen from recipes provided in the book.

After the Diet

You may repeat these two phases as often as desired for further weight loss.

However, you are encouraged to continue “sirtifying” your diet after completing these phases by incorporating sirtfoods regularly into your meals.

There are a variety of Sirtfood Diet books that are full of recipes rich in sirtfoods. You can also include sirtfoods in your diet as a snack or in recipes you already use.

Additionally, you are encouraged to continue drinking the green juice every day.

In this way, the Sirtfood Diet becomes more of a lifestyle change than a one-time diet.

Summary: The Sirtfood Diet consists of two phases. Phase one lasts seven days and combines calorie restriction and green juices. Phase two lasts two weeks and includes three meals and one juice.
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Are Sirtfoods the New Superfoods?

There’s no denying that sirtfoods are good for you. They are often high in nutrients and full of healthy plant compounds.

Moreover, studies have associated many of the foods recommended on the Sirtfood Diet with health benefits.

For example, eating moderate amounts of dark chocolate with a high cocoa content may lower the risk of heart disease and help fight inflammation (, ).

Drinking green tea may reduce the risk of stroke and diabetes and help lower blood pressure ().

And turmeric has anti-inflammatory properties that have beneficial effects on the body in general and may even protect against chronic, inflammation-related diseases ().

In fact, the majority of sirtfoods have demonstrated health benefits in humans.

However, evidence on the health benefits of increasing sirtuin protein levels is preliminary. Yet, research in animals and cell lines have shown exciting results.

For example, researchers have found that increased levels of certain sirtuin proteins lead to longer lifespan in yeast, worms and mice ().

And during fasting or calorie restriction, sirtuin proteins tell the body to burn more fat for energy and improve insulin sensitivity. One study in mice found that increased sirtuin levels led to fat loss (, ).

Some evidence suggests that sirtuins may also play a role in reducing inflammation, inhibiting the development of tumors and slowing the development of heart disease and Alzheimer’s ().

While studies in mice and human cell lines have shown positive results, there have been no human studies examining the effects of increasing sirtuin levels (, ).

Therefore, whether increasing sirtuin protein levels in the body will lead to longer lifespan or a lower risk of cancer in humans is unknown.

Research is currently underway to develop compounds effective at increasing sirtuin levels in the body. This way, human studies can begin to examine the effects of sirtuins on human health ().

Until then, it’s not possible to determine the effects of increased sirtuin levels.

Summary: Sirtfoods are typically healthy foods. However, very little is known about how these foods affect sirtuin levels and human health.

Is It Healthy and Sustainable?

Sirtfoods are almost all healthy choices and may even result in some health benefits due to their antioxidant or anti-inflammatory properties.

Yet eating just a handful of particularly healthy foods cannot meet all of your body’s nutritional needs.

The Sirtfood Diet is unnecessarily restrictive and offers no clear, unique health benefits over any other type of diet.

Furthermore, eating only 1,000 calories is typically not recommended without the supervision of a physician. Even eating 1,500 calories per day is excessively restrictive for many people.

The diet also requires drinking up to three green juices per day. Although juices can be a good source of vitamins and minerals, they are also a source of sugar and contain almost none of the healthy fiber that whole fruits and vegetables do ().

What's more, sipping on juice throughout the whole day is a bad idea for both your blood sugar and your teeth ().

Not to mention, because the diet is so limited in calories and food choice, it is more than likely deficient in protein, vitamins and minerals, especially during the first phase.

Due to the low calorie levels and restrictive food choices, this diet may be difficult to stick to for the entire three weeks.

Add that to the high initial costs of having to purchase a juicer, the book and certain rare and expensive ingredients, as well as the time costs of preparing specific meals and juices, and this diet becomes unfeasible and unsustainable for many people.

Summary: The Sirtfood Diet promotes healthy foods but is restrictive in calories and food choices. It also involves drinking lots of juice, which isn’t a healthy recommendation.
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Is It Effective?

The authors of the Sirtfood Diet make bold claims, including that the diet can super-charge weight loss, turn on your “skinny gene” and prevent diseases.

The problem is there isn’t much proof to back them.

So far, there’s no convincing evidence that the Sirtfood Diet has a more beneficial effect on weight loss than any other calorie-restricted diet.

And although many of these foods have healthful properties, there have not been any long-term human studies to determine whether eating a diet rich in sirtfoods has any tangible health benefits.

Nevertheless, the Sirtfood Diet book reports the results of a pilot study conducted by the authors and involving 39 participants from their fitness center. However, the results of this study appear not to have been published anywhere else.

For one week, the participants followed the diet and exercised daily. At the end of the week, participants lost an average of 7 pounds (3.2 kg) and maintained or even gained muscle mass.

Yet these results are hardly surprising. Restricting your calorie intake to 1,000 calories and exercising at the same time will nearly always cause weight loss.

Regardless, this kind of quick weight loss is neither genuine nor long-lasting, and this study did not follow participants after the first week to see if they gained any of the weight back, which is typically the case.

When your body is energy deprived, it uses up its emergency energy stores, or glycogen, in addition to burning fat and muscle.

Each molecule of glycogen requires 3–4 molecules of water to be stored. When your body uses up glycogen, it gets rid of this water as well. It’s known as “water weight.”

In the first week of extreme calorie restriction, only about one-third of the weight loss comes from fat, while the other two-thirds comes from water, muscle and glycogen (, ).

As soon as your calorie intake increases, your body replenishes its glycogen stores, and the weight comes right back.

Unfortunately, this type of calorie restriction can also cause your body to lower its metabolic rate, causing you need even fewer calories per day for energy than before (, ).

It is likely that this diet may help you lose a few pounds in the beginning, but it will likely come back as soon as the diet is over.

As far as preventing disease, three weeks is probably not long enough to have any measurable long-term impact.

On the other hand, adding sirtfoods to your regular diet over the long-term may very well be a good idea. But in that case, you might as well skip the diet and start doing that now.

Summary: This diet may help you lose weight because it is low in calories, but the weight is likely to return once the diet ends. The diet is too short to have a long-term impact on your health.
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Safety and Side Effects

Although the first phase of the Sirtfood Diet is very low in calories and nutritionally incomplete, there are no real safety concerns for the average, healthy adult considering the diet’s short duration.

Yet for someone with diabetes, calorie restriction and drinking mostly juice for the first few days of the diet may cause dangerous changes in blood sugar levels ().

Nevertheless, even a healthy person may experience some side effects — mainly hunger.

Eating only 1,000–1,500 calories per day will leave just about anyone feeling hungry, especially if much of what you’re consuming is juice, which is low in fiber, a nutrient that helps keep you feeling full ().

During phase one, you might experience other side effects such as fatigue, lightheadedness and irritability due to the calorie restriction.

For the otherwise healthy adult, serious health consequences are unlikely if the diet is followed for only three weeks.

Summary: The Sirtfood Diet is low in calories and phase one is not nutritionally balanced. It may leave you hungry, but it’s not dangerous for the average healthy adult.
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The Bottom Line

The Sirtfood Diet is full of healthy foods, but not healthy eating patterns.

Not to mention, its theory and health claims are based on grand extrapolations from preliminary scientific evidence.

While adding some sirtfoods to your diet is not a bad idea and may even offer some health benefits, the diet itself looks like just another fad.

Save yourself the money and skip to making healthful, long-term dietary changes instead.

An evidence-based article from our experts at Authority Nutrition.
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