What is the Sirtfood diet?

If you've ever considered following a weight loss diet, make sure you have all the facts first. Dietitian Emer Delaney takes a look at the Sirtfood diet.

A glass of red wine next to some dark chocolate

What is the Sirtfood diet?

Launched originally in 2016, the Sirtfood diet remains a hot topic and involves followers adopting a diet rich in ‘sirtfoods’. According to the diet's founders, these special foods work by activating specific proteins in the body called sirtuins. Sirtuins are believed to protect cells in the body from dying when they are under stress and are thought to regulate inflammation, metabolism and the aging process. It's thought that sirtuins influence the body’s ability to burn fat and boost metabolism, resulting in a seven pound weight loss a week while maintaining muscle. However, some experts believe this is unlikely to be solely fat loss, but will instead reflect changes in glycogen stores from skeletal muscle and the liver. 

Sliced fresh oranges on a blue background

The diet 

So what are these magical ‘sirtfoods’?  The ten most common include:

  • Green tea
  • Dark chocolate (that is at least 85 per cent cocoa)
  • Apples
  • Citrus fruits
  • Parsley
  • Turmeric
  • Kale
  • Blueberries
  • Capers
  • Red wine

The diet is divided into two phases; the initial phase lasts one week and involves restricting calories to 1000kcal for three days, consuming three sirtfood green juices and one meal rich in sirtfoods each day. The juices include kale, celery, rocket, parsley, green tea and lemon. Meals include turkey escalope with sage, capers and parsley, chicken and kale curry and prawn stir-fry with buckwheat noodles. From days four to seven, energy intakes are increased to 1500kcal comprising of two sirtfood green juices and two sirtfood-rich meals a day.

Although the diet promotes healthy foods, it's restrictive in both your food choices and daily calories, especially during the initial stages. It also involves drinking juice, with the amounts suggested during phase one exceeding the current daily guidelines.

The second phase is known as the maintenance phase which lasts 14 days where steady weight loss occurs. The authors believe it’s a sustainable and realistic way to lose weight. However, focusing on weight loss is not what the diet is all about – it’s designed to be about eating the best foods nature has to offer. Long term they recommend eating three balanced sirtfood rich meals a day along with one sirtfood green juice.

A woman standing on weighing scales in a bathroom

Dietitian Emer Delaney says:

‘At first glance, this is not a diet I would advise for my clients. Aiming to have 1000kcal for three consecutive days is extremely difficult and I believe the majority of people would be unable to achieve it.  Looking at the list of foods, you can see they are the sort of items that often appear on a ‘healthy food list’, however it would be better to encourage these as part of a healthy balanced diet. Having a glass of red wine or a small amount of chocolate occasionally won’t do us any harm - I wouldn’t recommend them on a daily basis. We should also be eating a mixture of different fruits and vegetables and not just those on the list.

‘In terms of weight loss and boosting metabolism, people may have experienced a seven pound weight loss on the scales, but in my experience this will be fluid.  Burning and losing fat takes time so it is extremely unlikely this weight loss is a loss of fat. I would be very cautious of any diet that recommends fast and sudden weight loss as this simply isn’t achievable and will more than likely be a loss of fluid. As soon as people return to their regular eating habits, they will regain the weight.  Slow and steady weight loss is the key and for this we need to restrict calories and increase our activity levels. Eating balanced regular meals made up of low GI foods, lean protein, fruit and vegetables and keeping well hydrated is the safest way to lose weight.’

Please note: if you're considering attempting any form of diet, please consult your GP first to ensure you can do so without risk to health.

Kale salad with tahini and lemon dressing in a dark bowl

Sirtfood recipes

These recipes contain foods that are promoted as part of the Sirtfood diet.

Matcha with vanilla
Turmeric tea
Date & walnut cinnamon bites
Red chicory, pear & hazelnut salad
Italian kale
Kale with lemon tahini dressing
Broccoli & kale green soup
Strawberry, tomato & watercress salad
Oriental salmon & broccoli traybake
Superhealthy salmon salad
Malabar prawns
Chicken, kale & sprout stir-fry
Chicken, broccoli & beetroot salad

More information...

Weight loss and good health can be achieved by following a healthy, balanced diet. Our nutritionist approved plan helps you find your perfect portion size, guideline daily amounts and nutritionally balanced breakfasts, lunches, dinners and snacks:
A balanced diet for women
A balanced diet for men

Want facts and information on other diets? Read more from our health editor and nutritionist on other popular weight loss plans:

The Atkins diet
The Dukan diet
The Paleo diet
The 5:2 diet

This page was last reviewed on 19th February 2020 by Kerry Torrens.

Emer Delaney BSc (Hons), RD has an honours degree in Human Nutrition and Dietetics from the University of Ulster. She has worked as a dietitian in some of London's top teaching hospitals and is currently based in Chelsea.

Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.

All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.

Have you tried a Sirtfood diet? Share your stories below...

Comments, questions and tips

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26th Sep, 2017
It's weird having a good food magazine giving any space to diets . Shame on this type of journalism .
goodfoodteam's picture
11th Mar, 2020
Thanks for taking the time to comment. We work with dietitian’s to provide unbiased, clear and factual advice on popular diets. This is not an endorsement and when a diet is unsafe, unbalanced or unworkable for the long term we clearly say so.
1st Oct, 2016
My brother has been on the Sirt diet for 3 months and has lost a lot of weight - I have to say though that he follows the diet strictly, no deviations. He is 76 years old and I hadn'5 seen him for a year until yesterday; yes I'm pleased for him having lost the weight, but to my eyes he looks gaunt. I was curious about the diet - many of these foods I eat already. I shall not be following this diet - to me diets cannot be sustained, a permanent change in eating habits so that food intake is balanced is far better
29th Aug, 2016
I've just done 7days on the sirt diet. Was very disappointed with my 1lb weight loss! Yes folks, that was 1 not a 7lb loss as it says in the book
15th Jun, 2016
Emer Delaney sadly hasn't actually read the Food Diet book or she wouldn't have made such stupid comments. The book discusses the trial carried out at a London gym where 40 volunteers followed the diet. They chose people who where already active and losing weight so that the initial fluid weight loss would not give false results. The idea of the first days being a fast is to kick the body into fat burning and repair. Meals are replaced with highly nutritious juices made from foods that activate fat burning. The food that is eaten is tasty, filling and portions are large. I have not been hungry. My husband had lost just over a stone and a half through eating healthily and taking exercise he wanted to lose another half a stone. I had decided to start the Sirt Food diet to lose weight gained after injury and suggested he join me. He was reluctant but did so. He lost 7lbs in the first week, this was certainly not fluid. I have also lost over 7 lbs and continue to lose weight even though I have a leg in plaster following surgery. This diet is amazing. It is nourishing, the food is tasty and the results are so good. I will keep sirt foods in my diet after I have reached my goal weight. I guess a nutritionist will have to warn against it, if people got good advice from a £2.99 book she'd be out of business.
goodfoodteam's picture
11th Mar, 2020
Thanks for taking the time to comment. I can confirm that I have read The Sirtfood Diet book and have noted the small study carried out in the London gym. To clarify, the aim of the above article is to provide an impartial, expert opinion on the diet for anyone who may want to follow it. As a specialist dietitian, I can confirm that it's not possible for any food or juices to 'activate fat burning'. Our bodies are extremely complicated and affected by a huge range of variables. Burning and losing fat takes time, so any rapid reduction in weight will be down to fluid losses rather than fat. In my professional opinion, the Sirtfood diet is not balanced nor healthy, and does not address relationship with food for long-term lifestyle changes. On this basis, I would not recommend it for my clients.
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