It's the eating regime that's said to be behind Adele's dramatic 7-stone weight loss and it involves coffee red wine and chocolate. We asked dietitians to decode it

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When photos of Adele looking dramatically slimmer emerged recently, talk quickly turned to how the singer had lost a reported seven stone. Reports claimed that  The Sirtfood Diet  by Aidan Goggins and Glen Matten, who both hold masters degrees in nutritional medicine, was the reason. In a TV interview in January, Adele’s former personal trainer Camila Goodis  said she believed Adele was working out, but 90 per cent of her weight loss was down to the diet.

The Sirtfood Diet is a metabolism-boosting plan that allows you to drink red wine and coffee as well as eat chocolate, which sounds like the dream. But we all know that there's no such thing as a magic weight-loss bullet, so we asked dietitians Sophie Medlin of City Dietitians  and Lola Biggs, dietitian at supplement brand Together Health  to do a little digging into all things sirtfood and decode how easy it is for mere mortals to follow.

What is The Sirtfood Diet?

“The theory behind The Sirtfood Diet is that there are certain foods that we can eat which increase our production of a group of proteins called sirtuins,” explains dietician Sophie. “Sirtuins are thought to do a number of jobs including supporting our bodies to be energy efficient during low-calorie situations such as when we’re dieting. The idea behind the diet seems to be that if you eat foods that may help you to produce more sirtuins, you will burn fat more efficiently and your metabolic rate will increase.”

The Sirtfood Diet authors say it's a way of shifting weight without radically dieting, because it activates the same 'skinny gene' pathways usually activated through fasting and exercise. "Certain foods contain chemicals called polyphenols that put mild stress on our cells, turning on genes that mimic the effects of fasting and exercise. Foods rich in polyphenols-including kale, dark chocolate and red wine-trigger the sirtuin pathways that impact metabolism, ageing and mood. A diet rich in these sirtfoods kick-starts weight loss without sacrificing muscle, while maintaining optimal health," they say.

There are studies that back the idea of foods such as chilli and green tea for weight loss and red wine (rich in polyphenols) is often cited major part in the French Paradox, the theory behind why French women drink red wine but stay slim. But so far there's no scientific evidence we can rely on to say whether the sirtfood theory works. There is some lab  research  to show that sirtuins may have an antiageing effect, but studies have been on mice, human stem cells and rats - not real-world people.

What foods can you eat on The Sirtfood Diet?

These are the top 20 foods said to increase your levels of metabolism-boosting proteins called sirtuins. It's recommended to have around 10 portions of sirtfoods a day for weight loss (the broadest range possible, so only two red wines - but still!) and five for maintenance.

• 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 chilli

• Lovage

• Medjool dates

• Red chicory

• Blueberries

• Capers

• Coffee

You might notice red wine and chocolate on the allowed food lists, which could account for some of the success. A big part of the diet is the green juice, containing 75g kale, 30g rocket, half a green apple, 1cm ginger, 2 sticks celery, half a lemon, 5g parsley and half teaspoon matcha which needs to be made with a juicer (as opposed to a blender) and a kitchen scale, as the ingredients are listed by weight.

What are the phases of the Sirtfood Diet?

It’s not just about eating sirtuin-producing foods to lose weight though; you also to have to cut your calories. Phase One lasts seven days and for the first three you consume 1000 calories per day via three green juices (recipe below) and one meal, all of which contain sirtfoods. Then it’s upped to 1,500 a day, two juices and two meals for the rest of the Phase One week.

“Everyone would lose weight on such a strict calorie restriction so there's no magic there,” says Sophie.

In Phase Two (two weeks) there’s no calorie limit, just three sirtfood-rich meals and one juice, none of which are moreish enough or carb-rich to really get fat on, so you may be eating fewer than you normally would anyway.

“The issue with The Sirtfood Diet is in the determining whether it is the work of the selected foods (rich in sirtuins) or the overall calorie restriction which drives the changes,” adds Lola.

Do dietitians recommend The Sirtfood Diet?

When the foods seem healthy enough, and you can pretty much dine out on Sirtfood Diet, is it a good call?

The pros: “From a nutritional density view, foods containing high levels of sirtuins also provide good levels of nutrients which are overall linked to improved health," says Lola. "This alongside calorie restriction will give results," says Lola.

“It may be that the allowance of foods that are usually considered taboos when dieting is actually the secret to the success of the plan,” says Sophie. “If you feel you can have foods like chocolate and red wine, it is likely that you feel less restricted than you might if you banned those foods from your diet.”

The cons: "Keeping this up long term can prove very difficult and often requires big shifts," she adds. "Life changes and restrictions which may not all be positive. Also, the impact on our mood with weight regain post-diet has been identified as a major drive in returning to comfort eating and less healthy eating habits.”

Nutritionist Daniel O'Shaughnessy  also has his doubts on how easy the diet is to maintain if you're not an A-lister. "The food can be hard to prepare for busy lifestyles and it's a bit of a faff to get it right and include the foods you need to. It can easily work for Adele as she doesn’t need to prepare everything, but people may find it a bit tricky balancing a job and children."

“We certainly won’t be recommending The Sirtfood Diet in my clinics or as a medical treatment for weight loss,” says Sophie. “While we may encourage some of the healthy foods, strict regimes and replacing meals with juices often lead to difficulties with people’s relationship with food and can lead us to lose sight of how much weight loss is too much.”

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