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All you need to know about the Sirtfood Diet

Adele’s dramatic weight loss transformation has got everyone discussing the new Sirtfood Diet, but is it as beneficial as it claims to be?

By now, we’ve all heard of the Sirtfood Diet, or at least we’ve seen the effects of it with Adele’s dramatic weight-loss photo that went viral this spring. The singer has reportedly lost three stone and accredits her transformation to a new diet that advocates chocolate, red wine and spending less time in the gym. With such enticing claims, who wouldn’t be intrigued to give it a go? But dig a little deeper, and you'll see health experts debating its sustainability. We’re here to tell you everything you need to know about the latest international diet sensation, which may make you think twice before adopting this plan.  

What are sirtfoods?

Let’s start with the basics and discuss what is considered a sirtfood and why it’s suddenly so popular. This strange new term was coined in 2003 to describe a group of ‘wonder foods’ that activate our 'skinny genes'. Now, this is an eye-catching way of saying certain foods help our body to burn fat. The genes in question are actually called sirtuin genes; these genes produce signalling proteins called sirtuins which are claimed to help our bodies to be energy efficient and slow down the effects of ageing [6].

The theory is that specific foods trigger our genes to produce sirtuins, which may help metabolise (burn) stored fat, in the same way that exercise and fasting do. Foods, such as dark chocolate and red wine, contain chemicals (polyphenols) which may mildly stress our cells, and thereby activate the sirtuins to mimic the effects of fasting and exercise. The Sirtfood Diet plan encourages an increased intake of these healthy sirtfoods to optimise the sirtuins’ potential. 

A diet that includes our guilty pleasures while still helping us to lose weight? It seems to be the best of both worlds. 

What can you eat?

Aside from the headline-grabbers, a huge number of foods contain polyphenols (sirtuin activators), so there is a multitude of sirtfoods included in the diet plan. If you’re trying to lose weight, the diet recommends you have 10 portions of sirtfoods per day, and 5 portions for maintenance. These portions need to be of the broadest range possible, so alas, you can’t just consume chocolate and red wine and still expect to be healthy.  Some of the foods high in sirtuin activators include:
•    Red wine
•    Green tea
•    Coffee
•    Dark chocolate (at least 85% cocoa)
•    Citrus fruits
•    Strawberries
•    Buckwheat
•    Soy
•    Red onion
•    Kale
•    Celery

What is The Sirtfood Diet plan?

As well as just advocating the consumption of sirtfoods, this diet has a specific plan that makes great claims to bring “a big difference from little changes” with “big boosts in energy, mood, and well-being, while slashing the risk of chronic disease” [1].

The diet plan lasts three weeks in total and is split into two phases:

Phase 1: (7 days)

Day 1-3: Each day, you have 3 sirtfood green juices and one full meal that’s also rich in sirtfoods. Your intake is limited to 1000 calories per day. 

Day 4-7: You now have 2 sirtfood green juices daily and two full meals rich in sirtfoods. Your intake is allowed up to 1,500 calories per day. 

Phase 2: (14 days)

You have one sirtfood green juice and eat three full meals every day, which should be balanced and rich in sirtfoods. 

After these three weeks, there is no set plan, but it is advocated that your daily life is adjusted to include as many sirtfoods as possible. If you want to find out more about the diet plan or specific recipes, you can visit the official website for more information, or purchase the original book. 

Does it work?

So, is this the answer to everyone’s weight loss dilemmas, or is it yet another fad that promises too much and can’t deliver? The published book claims that this is “a whole new way of eating that brings fantastic benefits for everyone” [1], but such a broad claim, which is currently lacking in robust scientific evidence, should not be taken literally. 

Now, there is no denying that these sirtfoods are healthy, and should definitely be included in your diet. The majority of the approved foods have high nutrient contents, and the list eliminates processed foods, refined carbs and added sugars which we know aren't healthy. However, the debate surrounds  the initial diet plan that restricts your calorie intake to 1000-1,500 per day which may be unsustainable in the long-run. In addition, the diet restricts intake of other nutrient rich food groups, such as dairy, so your diet may be at higher risk of lacking essential nutrients such as calcium.  

On average, participants of this plan tend to lose about 7lbs in one week. Although that can seem enticing, in an interview for BBC GoodFood, dietician Emer Delaney explains that this is likely just water weight – “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” [2]. Please note that the Sirtfood Diet plan does not comply with the NHS guidelines for weight loss, which recommends that the average person aiming to lose weight should reduce their daily calorie intake by around 600kcal. The NHS also recommends that you consume a balanced and varied diet including all five food groups: Fruits and Vegetables, Starchy Carbohydrates (including wholegrains), Lean protein, Dairy and alternatives, and finally a small amount of Healthy Fat (oils and spreads).

To achieve the most sustainable weight loss, a small and achievable calorie deficit along with a gradual increase in exercise is currently recommended by health professionals. Also, no long-term guides are provided with the Sirtfood Diet, so it’s possible that after phase 2 of the diet plan, people will just return to their regular eating habits and quickly regain any weight they’ve lost.

Although it is an exciting and a rapidly updating area of research, currently robust evidence behind the diet is lacking; the role of sirtuins in relation to ageing and weight loss has primarily been done on mice [3], yeast and stem cells, without any direct translation to human subjects. 

Delaney continued to explain that a restrictive crash-course  diet may be difficult to stick to and instead, to achieve sustainable weight loss, advocates “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” [2].

One last thing

All in all, sirtfoods are a healthy and nutritious food group to include in your diet. The list of sirtfoods avoids processed foods which can only be beneficial. Polyphenols (the sirtuin activators) are found in most fruit and vegetables and wholegrain cereals, so eating more of these foods will improve the variety and quality if your diet. Although the initial two-phase plan may not be easy or sustainable, following a diet rich in sirtfoods along with other fruit and vegetables, whole grains, healthy fats and lean protein, is a healthy lifestyle to adopt.

In terms of weight loss, while sirtfoods are generally healthy, they may not benefit your weight loss any more than a reduction in calories. Perhaps the answer to Adele’s achievement lies less in her diet plan but more so in her determination, new-found headspace and motivation. Going through drastic life changes often gives us the drive to achieve new goals. So, bear in mind, no matter which diet plan you choose to adopt, it will only be as successful as the effort you choose to invest in it.  


References

[1] Goggins, A. and Matten, G. (2017). The Sirtfood Diet. New York: Gallery Books.

[2] Delaney, E. (2020) What is the Sirtfood diet? [online] BBC Good Food. Available at: https://www.bbcgoodfood.com/howto/guide/what-sirtfood-diet [Accessed 08/07/20].

[3] Giblin, W. Skinner, M. Lombard, D. (2014) Sirtuins: Guardians of Mammalian Health Span. [online] National Library of Medicine. Available at: https://pubmed.ncbi.nlm.nih.gov/24877878/ [Accessed 08/07/20].

[4] The Sirtfood Diet. (2020) About Us. [online] Available at: https://sirtfooddiet.net/ [Accessed 08/07/20].

[5] NHS (2019) Start the NHS weight loss plan. [online] Available at: https://www.nhs.uk/live-well/healthy-weight/start-the-nhs-weight-loss-plan/ [Accessed 08/07/20].

[6] Dang (2015) The controversial world of sirtuins [online] Drug Discovery Today: Technologies [online] Available at: https://www.sciencedirect.com/science/article/abs/pii/S1740674912000546