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Is your diet backed by science?

Tape measure round knife and fork

Looking to lose weight? Searching the web for a diet to help? Here’s Voice of Young Science member Rob Hagan on why many of these diets are based on nothing more than dodgy nutritional claims.

When it comes to diets the media loves an ‘expert’ and they’re happy to present a person as a specialist even if they have no real expertise to share. There’s a long queue of non-experts waiting to fill that void with their own personal thoughts, which are often based on dodgy science or lack any basis in science at all.

Recently, the Voice of Young Science (a network of early career researchers and scientists) evaluated the evidence behind a range of diets. Alongside this we invented some of our own diets and challenged the public to separate the ones that we had made up from those that had been presented as serious diets elsewhere. Give our quiz it a try – it’s harder than you might think…

Do diets really work?

People are keen for a solution to problems they can attribute to their diet, but is it acceptable for magazines and glossy supplements to exploit the public’s lack of understanding?

Our food is more than a daily chore, it gives us pleasure and if fad diets take that away from us we’re taking away things from our daily life that make us happy. People may argue that we have to sacrifice happiness for a health benefit, but very few diets are actually based on scientific understanding of healthy nutrition.

A recent study published in the Journal of the American Medical Association found that there was little difference between diets in terms of weight loss. Any dietary restriction that we place upon ourselves will result in us losing weight as we eat less.

For example, if you decided eating food was a waste of time and went on the No Food Diet – where you drink a nutrient rich food ‘substitute’ instead – there are still problems with losing your enjoyment of food, which is associated with depression. And depending on the fad diet of choice, you could also be starting down a path towards malnutrition.

Tips to spot fad diets

If you’re being sold a product or asked to believe a claim, then you deserve to know whether it’s based on evidence or imagination. Asking for evidence can help to distinguish the bogus from the beneficial, and there are a few rules of thumb that can help you weigh up new diet fads:

  • Immune boosting – you can’t and you don’t need to.
  • Detox – it’s a marketing myth – our body does it without pricey potions and detox diets.
  • Superfood – there is no such thing, just foods that are high in some nutrients.
  • Cleansing – you shouldn’t be trying to cleanse anything other than your skin or hair.

What do you think about all the weight-loss diets on offer? Have you ever followed one? And make sure to let us know how you did in our spoof diet quiz.

Which? Conversation provides guest spots to external contributors. This is from Rob Hagan, a member of the Voice of Young Science. All opinions expressed here are Rob’s own, not necessarily those of Which?.


I cannot understand why detox products and diets have been sold and advertised without being referred to Trading Standards. They should have disappeared from shelves long ago.

While I do not “diet” I am a massive fan of juicing and I juice every day. It’s awesome as i hate the taste of veg and it’s one way of getting it into my body. I also like the slim fast shakes. While I have never been on the sim fast diet every now and again i will replace a meal with a shake – Just so I can have my chocolate fix!

(The last time I posted a comment about this type of thing I had a very hurtful message about me still being fat – Please be nice if you want to reply.)

Lynn says:
9 October 2014

What people put into their bodies is their business. If someone wants to shovel in fried snickers, or be terrified of GMO, eat cruelty free potatoes or try to cleanse their auras with pinapple juice enemas…I don’t care. I care when others try to force their ideas and beliefs on me.

[This comment has been edited to align with our commenting guidelines. Thanks, mods]

Charles says:
10 October 2014

But they are forcing their ideas and beliefs on us. That’s the problem.

And sharing evidence based advice and the clever tips to spot these rubbish diets is great. More power to you.

It depends on what you juice and why.

Fruit juice is BAD. Eating fresh fruit is fine as the natural sugar is locked into fibrous cells and does not get released to the body until it is well through the digestive system (into the small intestine) where it causes little harm. Juicing fruit breaks down these cells so the sugars are available to the digestive system immediately.

Sugar is bad: fruit juice and smoothies are bad.

I juice on a morning just before i go for my morning walk with the dog, I juice different things, this morning i made a Turbo Express (1/4 small pineapple, 1/2 stick celery, 1 inch chunk of cucumber, 1 small handful of spinach leaves, 1 small piece of peeled lime, 2 apples – not Granny Smiths, 1/4 ripe avocado).

But my fave is the Ginger Zinger (2 carrots, 2 apples, 1 inch slice of lemon – wax free and with rind, ¼ inch of fresh ginger, 2 ice cubes).

It all depends on what is on offer at the shops.

I agree completely about you main points (Immune boosting, Detox, Superfood and cleansing). The problem is that so many of these “diets” are just blatant exercises to get you to buy certain products and/or are based on twaddle.

There is now much more research being put into our diets. Until now, so much recommendation has been based on ‘mass surveys’ with analysing the what/why. The result is that we have been strung along for years on ill advice.

The only things for sure that all doctors and nutrionists agree is that sugar and high carb foods are bad; we should avoid eating processed meats (bacon, salami, sausages, etc.) and eat minimal red meat (once or twice a month). Strangely, fat is not the enemy and it is safe in moderation. So stick with butter and wholesome milk.

Much is still unknown and I’m sure that we are in for some real surprises over the next decade.

Jane says:
13 October 2014

Please dietician and not nutritionist.

Charles says:
14 October 2014

Where did you get the ‘avoid eating processed meats’ from? There’s lots of scare stories about but my understanding is that the research is looking levels of consumption that are far higher than we should be worried about. Unless you’re scoffing bacon morning, noon and night.

All things in moderation imo.

One problem (there may be more) with processed meats is that they generally contain nitrites. These are preservatives and are needed to prevent growth of some very dangerous bacteria. They also help meat retain its colour, which is obviously of lesser importance. Nitrites are converted to carcinogenic nitrosamines. The problem is greatest when nitrites are heated at high temperature, for example when grilling or frying. I believe the problem is more serious than what you might imagine.

Jane says:
13 October 2014

I am constantly amazed by the level of ignorance of supposedly intelligent people and their implicit belief in dietary myths. It seems nutritionists rule with their nonsensical diet plans and their intent to get you spending on some ridiculous supplement! The utter naïveté of it all.

A balanced diet and enjoy your food – one of life’s great pleasures.

The number of times I’ve seen opinions of diets change – something was bad for you, now it’s not. Superfoods – rubbish. Supplements tailored to men or women – who needs these tablets? Unless you have a health problem leave such stuff alone or see your doctor.

My philosophy is some people are naturally slim, whatever they eat; some are more plump – the way we are made. Mess with your diet – eat too much and become obese, or diet unecessarily to become too thin – why? Nothing wrong with being the way you are made; be comfortable with it.

To avoid offence I recognise that some do have weight problems not of their own making, and do need treatment; no doubt a properly prescribed diet is then appropriate. But not a commercial one from people out to extract your money.
Sorry – sounds a bit of a rant.

MalcolmB says:
23 October 2014

According to Michael Mosley on BBC last night there is indeed such a thing as a superfood with examples being beetroot, watermelon and garlic which can all reduce blood pressure. Nothing to do with vitamins and minerals at all.

All foods can have beneficial effects – the danger is focusing on the latest fashion at the expense of a balanced diet. For another view, you could look at http://www.nhs.uk/Livewell/superfoods/Pages/what-are-superfoods.aspx.
“A well-conducted review of the current evidence from 2013 concluded that beetroot juice was associated with a modest reduction in blood pressure.

Garlic, for example, contains a nutrient alleged to help reduce cholesterol and blood pressure. But you’d have to eat up to 28 cloves a day to match the doses used in the lab – something no researcher has yet been brave enough to try

All unprocessed food from the major food groups could be considered ‘super’. All these foods are useful as part of a balanced diet.”

Providing you eat properly (try the Mediterranean diet), buying “superfoods” will be unlikely to harm you, and if you believe in them that, in itself, could be beneficial. Worth remembering that there is an industry out their ready to extract money from your wallet in exchange for their miracle foods.

MalcolmB says:
23 October 2014

I agree. What is interesting is that the benefit is not from the traditional nutrients. The TV trial was very artificial in simply using one food item with each group to show its effect, It would have been interesting to know how one group using all three items would have got on, i.e. whether there would have been additional benefit since each worked via a discrete mechanism. I like the idea of a varied diet but do not understand what ‘balanced’ is supposed to be balanced for?

I would like to have a gastric band fitted i am looking at all clinics but i dont know who is the safest, a good reputable one and good price, and a good follow up program. Any suggestions please

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