Adele's dramatic and noticeable weight loss made headlines around the English pop star's 32nd birthday when she posted this Instagram photo of her noticeably slimmer figure.
Numerous sources say that she dropped over 90 pounds.
So how did she do it?
Part of her transformation may be due to a diet she followed: the Sirtfood diet.
What is the Sirtfood Diet?
The Sirtfood diet is a diet plan created by two English nutritionists and followed by numerous celebrities in Europe.
The premise of the diet plan is to activate sirtuin genes. According to research, sirtuins have been linked to longevity for nearly 20 years [*].
Fasting and exercise activate sirtuin gene pathways, but the theory behind the Sirtfood diet is that there is another way to enable them as well: eating certain polyphenol-rich foods (AKA Sirtfoods).
In their book, The Sirtfood Diet, the authors claim that by eating a low-calorie diet rich in Sirtfoods, you can activate the body's sirtuin pathways, mimicking the longevity-enhancing effects of fasting and exercise, and achieve the body you want.
How Does the Sirtfood Diet Work?
The Sirtfood Diet by Aidan Goggins and Glen Matten outlines how to follow the diet plan.
On the book's cover, the diet claims that you can "eat your way to rapid weight loss and longer life by triggering the metabolic powers of Sirtfoods" and that the diet is "clinically proven to help you lose 7 pounds in 7 days."
The plan is very low-calorie and focuses specifically on a diet rich in sirtfoods. It's broken down into two phases.
Phase 1: 7 pounds in seven days
During the first three days of phase one, restrict your calories to 1,000 per day. During these days, you drink three glasses of green juice and eat one meal from the book's recipes.
On days 4-7 of week one, you are now allowed 1500 calories, including two green juices and two meals per day.
People who have tried the diet describe extreme hunger during this phase, which is not surprising considering the severe calorie restriction.
Phase 2: Maintenance
The "maintenance" phase keeps your quick weight loss going.
It lasts two weeks, and during this phase, there is no strict calorie restriction. You choose three meals from the book and drink one juice per day.
You can continue the first two phases until you get the results you want.
After the phases complete, you're encouraged to continue "sirtifying" your diet by regularly consuming foods from the list below and drinking one glass of green juice per day.
What are Sirtfoods?
Since the foods in this diet are all rich in beneficial polyphenols, you may benefit from adding these foods to your diet whether or not you follow the strict diet plan.
The list of the top 20 Sirtfoods outlined by the Sirtfood diet are as follows [*]:
- Red wine
- Extra virgin olive oil
- Dark chocolate (85% cocoa)
- Matcha green tea
- Arugula (rocket)
- Bird's eye chili
- Lovage (a plant also known as Sea Parsley)
- Medjool dates
- Red chicory
Sirtfood Green Juice Recipe [*]
- 75 grams (2.5 ounce) kale
- 30 grams (1 ounce) arugula (rocket)
- 5 grams parsley
- 2 celery sticks
- 1 cm (½-in) ginger
- ½ green apple
- ½ lemon
½ teaspoon matcha green tea
How Does the Sirtfood Diet Compare to Other Popular Eating Plans?
The Sirtfood diet includes some foods that are also part of other popular diets, such as keto, paleo, and Whole30. Here is a closer look at how the Sirtfood diet compares to more established diet plans.
Diet Comparison: Sirtfood vs. Ketogenic
Keto is all about getting into ketosis by eating a low-carb, high-fat diet. When you drastically cut carb consumption, your body starts burning fat for fuel instead of glucose.
Keto includes eating low-carb and high-fat foods that create a macronutrient profile of 75% fat, 20% protein, and 5% carbohydrates. Keto dieters are not as focused on calorie restriction as Sirtfood dieters are, although many people track their macros and calories on keto, especially when first starting out.
Due to the satiating nature of fat, people on the keto diet rarely feel hunger, if ever.
Keto has more scientific backing than the Sirtfood diet, having been linked to disease management and immune health. The keto diet has been shown to help minimize the symptoms of diabetes, reduce inflammation, improve cognitive function, and enhance weight loss.
Diet Comparison: Sirtfood vs. Paleo
Unlike the Sirtfood diet, Paleo does not require one to worry about overeating fat or counting calories. It is a diet based on biology.
The basis of the Paleo way of eating is to realign the food we eat with the food of our ancestors. Humans have existed for 200,000 years, but our current diet of processed foods has only been around for about 50 years. Paleo invites you to return to how your ancestors ate -- focusing on meats and vegetables. It bans processed foods, grains, legumes, sugar, and dairy.
Since the foods on the Sirtfood Diet list are plant-based, they would be acceptable on a Paleo diet. But not all Paleo foods would be appropriate for the Sirtfood diet.
If you want to increase your phytonutrient intake on Paleo, and potentially get some of the benefits of activating sirtuin pathways through your diet, consider adding Sirtfoods to your Paleo diet.
What about weight loss on Paleo? Paleo dieters may find themselves losing weight initially after cleaning up their diet, but can hit a plateau if they don’t keep an eye on calorie intake.
Diet Comparison: Sirtfood vs. Whole30
Essentially, the Whole30 diet is a more restrictive version of Paleo. It's a 30-day elimination diet better described as a temporary nutrition reset than a long-term weight loss strategy.
Like the Sirtfood diet, Whole30 has precise guidelines around what foods are acceptable.
Unlike Sirtfood, Whole30 discourages calorie counting, and the focus is on how you feel throughout the process of eliminating food groups from your diet and adding them back in after the end of 30 days.
Weight loss isn't a primary goal of Whole30, but due to the severe restriction on what you can eat during the 30 days, it's common to lose weight. It's also common to gain the weight back when you reintroduce your body to your regular diet.
Is the Sirtfood Diet Healthy?
The Sirtfood diet makes big promises for weight loss and overall healthspan. But very little scientific research has gone into testing the diet or verifying its effectiveness.
The studies on Sirtfood diet guidelines have been on mice, flies, or very small sample groups. The average of 7 pounds lost in the first week was self-reported by participants and not backed up by any outside research.
1,000 to 1,500 calories per day is very restrictive, making the diet hard to stick to for very long. Also, restricting calories to this level has been linked to binge eating and metabolic damage. When your body experiences long-term calorie restriction, it can go into starvation mode, meaning your body is not burning calories as effectively as it can. Ironically, this can prevent weight loss.
Because of the restrictive nature and minimal food choices on the Sirtfood diet, and the lack of scientific support for its long-term effectiveness, the keto diet and the Paleo diet are better options for effective weight loss and long-term health and wellbeing.