Sirtfood Diet For Weight Loss: How Does It Work?

When enough celebrities swear by a diet, it quickly becomes a popular weight loss plan. Recently, Adele and Pippa Middleton have been linked to the sirtfood diet. This diet is based on the premise that certain foods can help activate “skinny genes” which code for signaling proteins called sirtuins, which may promote weight loss (5).

The sirtfood diet was created by two U.K.-based nutritionists, Aidan Goggins and Glen Matten. They also wrote a book called “The Sirtfood Diet,” which details the diet plan and provides recipes.

You must be wondering—are skinny genes real? Does the science behind the sirtfood diet hold up? Let’s take a closer look.

What Is The Sirtfood Diet?

The theory behind the sirtfood diet is that foods containing specific nutrients—called polyphenols—can help activate sirtuins in your body. 

Sirtuins (SIRT1) are a type of protein that’s found in every cell of your body. These proteins are thought to possibly have the following health benefits (8):

• Increased metabolism
• Reduced inflammation
• Enhanced cellular repair
• Extended life span

According to Goggins and Matten, eating foods rich in polyphenols can help boost weight loss by increasing metabolism, reducing inflammation, and repairing cells.

The sirtfood diet is a mostly plant-based diet that includes foods that are high in polyphenols. 

Unfortunately, there isn’t much research to support the claims made by the creators of the diet. Most of the information about sirtfoods and weight loss comes from preliminary animal studies or test-tube experiments (12).

That being said, some foods on the sirtfood diet list—such as kale, blueberries, and green tea—have been linked to weight loss in observational studies.

Read More: Active Rest Day Benefits, Workouts, And Diet

How Does The Sirtfood Diet Work?

The sirtfood diet is a two-phase plan that lasts for three weeks. 

Phase 1

The first phase lasts for seven days and is considered the more restrictive phase. During this phase, you’re supposed to consume a maximum of 1,000 calories per day. 

On days one to three, you’re supposed to drink three sirtfood green juices and eat one sirtfood-rich meal per day.

On days four to seven, you’re supposed to consume two green juices and two meals per day. 

The goal of phase 1 is to jump-start weight loss.

Phase 2

The second phase is less restrictive and is meant to be followed for the remaining two weeks of the diet. 

During this phase, you gradually add more calories and solid foods back into your diet. By the end of phase 2, you should be eating three sirtfood-rich meals and one green juice per day.

The goal of this phase is to help you lose weight steadily and keep it off in the long term.

After The Diet Phases

After three weeks of the diet are up, you need to continue following the principles of the diet but with a few tweaks. 

For example, you can add in one extra sirtfood-rich meal per day or swap out a green juice for a smoothie.

You can also indulge in your favorite sirtfoods—in moderation—a couple of times per week. This is meant to help you stick to the diet long-term.

What Can You Eat And What Can’t You Eat?

The list of top 20 sirtfoods, as outlined by Goggins and Matten, is mostly made up of plant-based foods. However, it also includes some animal-based foods, such as dark chocolate and red wine. 

Here are the 20 sirtfoods that are emphasized on the diet (9):

• Kale
• Blueberries
• Arugula
• Capers
• Red onion
• Parsley
• Olive oil
• Matcha green tea
• Strawberries
• Walnuts
• Dark chocolate (85% cocoa or higher)
• Coffee
• Citrus fruits
• Buckwheat
• Soy
• Red wine
• Red chicory 
• Medjool dates
• Bird’s eye chili
• Lovage

The polyphenols in these foods are what make them sirtfoods. These nutrients have been linked to a variety of potential health benefits, including weight loss (14).

While the list of sirtfoods is mostly made up of healthy plant-based foods, there are a few indulgences included, such as dark chocolate and red wine. 

These foods can still be part of a healthy diet—it’s just important to consume them in moderation.

In general, you should aim to fill your diet with mostly whole, minimally processed foods. These are the types of foods that are richest in polyphenols and other nutrients. 

Highly processed foods, on the other hand, tend to be low in polyphenols and high in calories, sugar, and unhealthy fats (15).

What foods are not allowed on the Sirtfood diet? Here are some examples:

• Processed meats
• Full-fat dairy products
• Refined carbs, such as white bread and pasta
• Sugary foods and drinks, such as candy and soda
• Unhealthy fats, such as butter and margarine
• Alcohol (other than red wine)

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What Is A Typical Sirtfood Meal?

The actual meal ideas and recipes for people on this diet can be found in the book, The Sirtfood Diet. 

But in general, a typical sirtfood meal contains ingredients from the list of sirtfoods. For example, a meal might include kale, strawberries, and olive oil. 

Or, a meal might include buckwheat noodles with chicken and bird’s eye chili peppers. 

There are many different combinations that you can make with the allowed foods. 

Green juices are also a key part of this diet. These juices are made with sirtfoods, such as kale, parsley, and blueberries.

Here are some sirtfood-based meal ideas:

Breakfast On The Sirtfood Diet

• A green juice made with kale, parsley, celery, cucumber, and ginger
• Overnight oats made with buckwheat groats, almond milk, and blueberries
• A smoothie made with strawberries, Matcha green tea powder, and soy milk
• Avocado toast with roasted red chicory

Lunch On The Sirtfood Diet

• A salad made with arugula, walnuts, and Medjool dates
• A soup made with kale, potatoes, and leeks
• Buckwheat noodles with chicken and bird’s eye chili peppers
• Quinoa bowl with roasted vegetables and olive oil

Dinner On The Sirtfood Diet

• Grilled salmon with asparagus and lemon
• Roasted chicken with Brussels sprouts and red onions
• Vegetable stir-fry made with tofu, broccoli, and red peppers
• Spaghetti squash with tomatoes, garlic, and basil

Snack Ideas On The Sirtfood Diet

• A handful of walnuts
• A small piece of dark chocolate (85% cocoa or higher)
• 1/2 an avocado with sea salt and pepper
• 1 cup of berries
• 10 raw almonds
• Veggies and hummus

How Much Weight Can You Lose On The Sirtfood Diet?

This diet uses a combination of sirtfoods and calorie restriction to promote weight loss. 

The promised weight loss is 3 to 5 pounds in the first week and 1 to 2 pounds every week after that. 

However, these results are not based on any scientific research. There is no scientific evidence to support the claims made about this diet. 

The weight loss that does occur is likely due to the calorie restrictive aspect of the diet and not the sirtfoods themselves (7). 

Furthermore, the safe amount of weight to lose in a week is 1-2 pounds (6). Losing more than this amount of weight per week is not sustainable and can lead to health problems.

Therefore, if you’re considering this diet, it’s important to do so with realistic expectations.

Read More: No Carb No Sugar Diet Meal Plan: Is It Healthy For Weight Loss?

Things To Consider Before Trying The Sirtfood Diet

This diet may help you lose weight in the short term, but it’s not a sustainable or healthy way to eat long-term. Here are a few reasons why.

Extreme Restriction

For the first 7 days of this diet, you’ll be consuming no more than 1,000 calories a day. 

This is a very low-calorie intake, which can lead to side effects like fatigue, hunger, and irritability. 

The average woman needs around 2,000 calories a day to maintain her weight, while the average man needs 2,500 (1). 

A healthy and sustainable calorie deficit for weight loss is 500 calories a day for women and 700 for men. 

That said, this diet is significantly below what’s considered safe and healthy.

Not Enough Protein

Protein is an essential nutrient that helps with weight loss, muscle growth, and recovery (2). 

The recommended minimum daily intake (RDI) of protein is 0.8 grams per kilogram of body weight (3). 

However, the average person needs more than this amount to meet their protein needs. 

For example, active women may need up to 75 grams or more of protein per day, and active men may need up to 125 grams or more. This is especially true when following a weight loss diet.

The Sirtfood Diet only includes 15-20 grams of protein per day, which is far below what’s needed.

Lack Of Vitamins And Minerals

This diet is also lacking in certain essential vitamins and minerals.

For example, it’s very low in iron, calcium, and vitamin B12. These nutrients are essential for overall health and well-being. 

Additionally, the lack of variety in many weight loss diets including this diet may lead to nutrient deficiencies over time (10). 

Some Sirtfoods Aren’t Necessarily Healthy

Just because a food is considered a “sirtfood” doesn’t necessarily mean it’s healthy. For example, dark chocolate is a sirtfood, but it’s high in calories and saturated fat. It’s fine in moderation, but overdoing it just because it’s on the list isn’t a great idea.

Unless you understand the principles of healthy eating and how to make nutritious choices, you might not lose weight on this diet. 

Risk Of Disordered Eating

Eating disorders are serious mental health conditions that can be triggered by restrictive diets (4). The Sirtfood Diet is an extreme diet that requires you to severely restrict your food intake. 

This level of restriction can be dangerous, especially for people who are vulnerable to disordered eating (4). 

If you have a history of disordered eating, it’s important to speak with a doctor or registered dietitian before trying this or any other restrictive diet.

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Cost Of Seasonal Ingredients

The foods on the Sirtfood Diet are not cheap. For example, arugula, kale, and wild salmon can be costly, especially if you’re buying organic. 

Additionally, the diet recommends that you drink three cups of green juice per day. Juicing also requires special equipment, which can add to the cost. 

You may also need to invest in some of the cookbooks offered on the official website, which can be pricey as well. 

In reality though, weight loss doesn’t have to be costly. There are plenty of healthy foods that are affordable and easily accessible. 

Social Isolation

The Sirtfood Diet can be difficult to follow when eating out or socializing with friends and family. 

This is because restaurants and most social gatherings revolve around food, and the foods allowed on this diet are very specific. 

You may find yourself feeling left out or isolated if you stick to this diet long-term. 

A Better Alternative For Healthy Weight Loss

At the core of most fad diets and popular weight loss programs is extreme calorie restriction (11). 

While this may lead to short-term weight loss, it’s not a sustainable or healthy way to lose weight.

A better alternative is to focus on eating a healthy diet that includes plenty of fruits, vegetables, whole grains, and lean protein (16). 

Reduce your calorie intake by 500-1,000 calories per day from your usual intake to lose 1-2 pounds per week. This rate of weight loss is safe and sustainable for most people. 

You can achieve this by eating smaller portions and cutting out ultra processed and high-calorie foods.

You can also focus on creating a calorie deficit by increasing your activity level and burning more calories than you consume (13). Choose the exercise plan that fits your lifestyle and preferences, and make sure it’s something you’ll stick with long-term. 

This approach is more likely to lead to sustainable weight loss, without the risk of nutrient deficiencies or disordered eating. 

The Bottom Line

The Sirtfood Diet is a restrictive weight loss diet that’s based on eating specific foods that are claimed to boost metabolism and promote fat loss. 

However, this diet is very low in calories, lacks essential nutrients, and some of the “sirtfoods” aren’t necessarily healthy.

Additionally, the diet is lacking in essential nutrients, and it’s not a sustainable or healthy way to eat long-term. 

If you’re considering this diet, be sure to do so with realistic expectations and under the supervision of a doctor or registered dietitian.