The Sirtfood Diet: the latest in a long list of BS faddy diets clients, friends, and family, have sent me for my professional critique. I figured that if they were asking, then other people must have questions too. This is a pretty lengthy article so here's the TL:DR - this diet is bogus, don't get the book, work with a qualified nutritionist instead.
Still with me? Let's break it down.
First of all, we need to understand what sirtfoods are, and to understand that, we need to know what sirtuins are. Y'all ready for a little science? Here we go.
Sirtuins are a group of proteins known as Silent Information Regulators, or SIRs. They were discovered in humans a few decades ago, and have been aggressively studied since then, mostly at a subcellular level or in lab animals (i.e. not many studies in actual human people). This has led scientists to make exciting discoveries about the role of these proteins in protecting metabolic health, including: regulation of our biological clocks (aka circadian rhythm), reducing inflammation, mopping up free radicals that can cause damage to DNA, helping to protect the integrity of our DNA and prevent it from premature ageing; therefore SIRs may play an important role in prevention of Alzheimer's. Scientists also think they may be important in protecting against (and maybe even treating) disease like type 2 diabetes, cardiovascular diseases like heart attacks and stroke, and even some cancers. Pretty exciting stuff, right? Right! But it's important to say that, although these findings are promising, they're 1) reductionist in nature (i.e. we don't just eat only sirtfoods) and 2) we don't have many studies in humans yet.
Anyway, sirtuins have been implicated in preventing fat cells from duplicating, a phenomenon known as adipogenesis (adipose cells being the latin for fat) (lol jk, but adipose does mean fat). It was at this point that the authors of 'The Sirtfood Diet' heard a 'KA-CHING' and saw little $$ floating in front of them.
So, the theory is then, that certain foods can upregulate the expression of the SIR genes. All that means is that certain foods send messages to our DNA to tell them to make more of the sirtuin proteins. So, more sirtfoods=more sir proteins. Got it? It's a little more complicated than that, but you get the idea.
The authors of TSD, took this a step further and basically came to the conclusion that if you make a diet up of a bunch of these so called 'sirtfoods' you'll not only blast people's fat cells and make them loose a bunch of weight, but they'll effectively become immortal in the process.
The diet is broken down into three stages as explained here, but in brief: The "Hyper Success Phase" (inspired naming there guys), whereby dieters are restricted to 1000kcals per day made up of three sirtfood green juices and a sirtfood rich meal. For three days straight. Phase two then, gets an additional 500kcal, because you ditch one of the juices and replace it with actual food - sirtfoods though. Remember that, it's important. At the end of the week you go into the maintenance phase of 3 sirtfood rich meals plus a sirtfood juice.
The authors put this diet to the test in their elite, private members gym, where participants (n=40) received training sessions with a personal trainer and were under the authors' expert nutritional guidance. They paid around £1,500 for the privilege too. I think we'd all agree that this was a rigorous and replicable study, no?
Full disclosure: I have not read the book (hey, no one sent me an advance copy and no one's paying me for writing this shit). Anyway, based on what I can garner from the popular press (and yes I know it would not stand up as a legitimate source in the court of science, but just stick with me), here are all the problems I have with The Sirtfood Diet. A rebuttal, if you will.
7lbs in 7 days
So, the big claim from TSD is that you can lose 7lbs in 7 days. Goggins and Matten claim that their diet is not about weight loss, it's about health, but this 7 in 7 is central to their marketing strategy. It's plastered all over the front cover of the book FFS. Not only is this kind of weight loss unsustainable, dramatic, and unhealthy, it can be psychologically damaging to set someone up with this kind of unrealistic expectation of the diet. 1-2lbs per week is the recommendation for weight loss. It doesn't happen overnight, it's slow and gradual and hella frustrating. My guess is that it didn't all go on overnight, so we need to have realistic expectations about losing it too.
Calorie Restriction Vs Sirtfoods
The second thing that really peeves me about this diet is that it's impossible to uncouple the effects of sirtfoods from calorie restriction. I mean, guys, where was the control group in your 'study'? Come on, that's like, basic shit. When you drastically restrict calories to 50% of what a person should normally consume, chances are, you're going to lose weight. I don't care if it's 1000ckals of bananas or biscuits, you gon' lose weight, son. Just at the anticipation of trolls; yes I know weight loss is more complex than that. Calories in =calories out is a gross oversimplification. I also know that long term calorie restriction can result in metabolic stagnation, which is why, I always recommend you work with a qualified professional when trying to shift some lbs. But you know, in general.
Are sirtfoods really even all that?
First of all, I really hate the term sirtfoods, it's a total misnomer. The foods recommended by the sirtfood diets: kale, green tea, blueberries, coffee, dark chocolate, red wine, rocket/arugula, parsley don't actually contain sirtuins. Certain phytonutrients (plant nutrients) in the foods promote or stimulate the production of these proteins (remember out little science chat?). Don't get me wrong, for the most part these foods are SUPER healthy (the red wine is questionable, I mean, alcohol is literally a toxin). But here's the thing, sirtfoods contain a shitload of health promoting phytonutrients . I'm talking ≥10,000 different compounds - not just the ones that promote sirtuin activity (polyphenols). We've got bioflavonoids, carotenoids, retinols, isoflavones, genistein, lycopene, sulphoraphones, and, you get the picture. But these compounds aren't exclusive to sirtfoods, nor do sirtfoods hold the rights to SIR promoting activity. The point is, eat a wide variety of plant based foods, like fruit, veg, and beans to get all them good phytochemicals, max your metabolism, and prevent disease. In other words, sirtfoods aren't all that, and thank to Goggins and his bud, they're going to be super spenny in the shops now too.
Sirtify your life
The authors have made statements about how all you gotta do is add a sirtfood twist to your favourite dishes. Right... So, what if your favourite meal is fried chicken? Or steak and chips? What these two dipshits need to get across is that foods high in fat and protein produce glycotoxins (or advanced glycation end products if you want to get fancy). Glycotoxins surpress sirtuin activity. Some are produced natuarally by the body, but mostly they come from the diet. The biggest dietary sources are chicken, beef, pork and fish, particularly if grilled or fried. And some scientists suggest that these are (at least partially) responsible for the 3X greater risk of dementia among meat eaters than among vegetarians. They've also been implicated in type 2 diabetes risk. So why then, are these guys telling you to eat chicken curry, and chilli con carne? A side of kale isn't gonna undo that, you have to look at the foods you eat as a whole.
Sirtfoods are not the only way to increase your sirtuin activity
Sirtuins are also produced through caloric restriction and exercise.
Focus on sirtjuices?
I've already talked at length about why juice cleanses are dumb, so I'll keep this brief. I think there is space in the diet for people to include green juice that is vegetable based. I don't think 2-3 juices, as replacements for actual wholefood meals is sound or responsible nutrition advice.
In the immortal words of Michael Pollan: "Eat food. Mostly plants. Not too much", and if you need help navigating that message, find yourself a nutritionist who can get on board with it.