/ Food & Drink, Health

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.