The 17 Biggest Food Myths of All Time

The term “carbs” may have become synonymous with bread and pasta but, in reality, they’re found in a variety of foods, from leafy greens to oats and lentils. “Are we seeing higher levels of obesity because we’re overeating oats and lentils? Not based on any current data,” says dietitian Ryan Andrews, who points out that body composition is “influenced by countless factors, from stress to sleep” – not just your partiality for buttery toast.

So, why the confusion? Eating carbs raises blood sugar levels, triggering the release of insulin, a hormone that controls fat storage. But this is a normal biological process and, as long as you’re feeding your body with the right amount of energy to meet its demands, there’s no reason you’ll put on extra padding.

True, some people lose fat on a low-carb plan: “Cutting back on carbs, like any other food, can put you in a calorie deficit,” says Famutimi. But it’s no magic bullet. Some of the healthiest people in the world eat plenty of carbs: only 4 per cent of Japanese men are classed as obese, even though rice and noodles are staples. 

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“Some people think if you eat carbs before going to sleep, they’ll have a negative effect because your metabolism will slow down,” says Famutimi. That’s false. What matters are your habits across a month. If you work out after 6pm, “Eat high-carb meals after your workouts, when your body craves nutrients,” says Famutimi.

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“Milk does a body good” was a 1980s marketing campaign that positioned dairy as the antidote to osteoporosis. And for the 40 per cent of adults globally who have no trouble digesting it, dairy has its benefits: it’s a source of vitamins D and B12, phosphorus and calcium. But tofu, soya milk, pak choi, kale, plus certain beans, nuts and seeds are also rich sources. 

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“It’s all about context,” says nutritionist Steve Grant. The glycaemic index (GI) ranks how carb-containing foods impact your blood sugar levels, but combining carbs with proteins, fats and fibre dampens the blood sugar response. A jacket potato, for example, might score highly, but a spoonful of tuna mayo and some avocado will bring its GI right down. “In fact, in some circumstances, high-GI carbs can even be beneficial,” Grant points out, “particularly when you want to replenish your glycogen stores after training.”

People react differently, too. “Our gut microbiome has been shown to influence the glycaemic index of a food,” says Grant. “We all have unique responses.”  The index is perhaps too crude a measurement.” 

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There’s a crucial difference between “supercharge” and “support”. Micronutrients, including B vitamins and certain minerals, will support healthy metabolic function. But a pinch of chilli powder or a spoonful of apple cider vinegar won’t help your body to incinerate kilojoules in any meaningful way. At best, they’ll assist with blood sugar balance and satiety. That may be less sexy, but it’s still useful.

“There was a time when people thought that if you took a spoonful of coconut oil before a workout, you would burn more fat,” says Famutimi. This, again, is specious. The MCT fats in coconut oil appear to improve fat oxidation compared to other forms of fat, but it’s a case of marginal gains – and won’t compensate for the fact that you’ve eaten a spoonful of oil.

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“Humans can survive and thrive on a variety of dietary patterns,” says Andrews. “But manipulating fat intake doesn’t appear to be as important to body composition as other factors, such as aiming to eat a high-quality diet – minimally processed, with plenty of plants.”

A ketogenic diet, in which 70 per cent or more of your kilojoules come from fat, pushes the body into a fasting-like state in which the body switches from using glycogen as a fuel source to using ketones. But it’s energy balance – not fuel source – that dictates weight loss and gain. 

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“There’s not a huge difference between ‘natural’ sweeteners and sugar,” says Grant. “There may be a few more micronutrients in sugars like molasses, date syrup and honey, but from a calorie and macronutrient perspective, they’re pretty much the same. So, it’s still important to be mindful of your intake.” in other words, factor those organic flapjacks into your recommended 30g daily limit.

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Flooding your body with synthetic vitamins in the hope of reaching nutritional nirvana does not work. Micronutrients offer diminishing returns: “Many are ‘hormetic’ – they have an increasingly beneficial impact up to a certain point, then above that, they begin to have an adverse effect,” says Roberts. Take, for example, vitamin C: the “upper tolerable limit” ­is 2000mg per day, after which you might experience side effects such as nausea or trouble sleeping. Read the labels and, if you’re worried about deficiencies, get a blood test before topping up.

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“Humans love categorical thinking,” says Andrews. “It’s not uncommon to hear people say that meat is a protein, wholegrains are a carbohydrate and nuts are a fat.” In reality, most foods contain a variety of macro- and micronutrients. 

Though it’s true that many plant-protein sources are “incomplete” – they don’t contain all nine essential amino acids – this is only a problem if there’s no variety in your diet. Vegans should eat one portion of legumes per day, such as chickpeas, to get the amino acid lysine.

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“This is a hot topic now,” says Roberts. It’s true that dieting for an extended period can cause your metabolism to slow. Cheat meals – or even cheat weeks – have been proposed as a way to prevent this. That could mean bringing your kiljoule intake up to maintenance levels (hardly cheating), or even introducing a surplus. “For the period when you’re refeeding, your metabolic rate might be restored,” says Roberts, “but studies suggest that it will fall again when you return to the diet.”

That’s not to say that boosting your kilojoule intake is of no benefit, however. A recent study noted that a break decreased “diet fatigue” – the boredom of being deprived of your favourite foods – “so it may help people adhere to an eating plan, and therefore see more weight loss”.

 Most nutritionists advocate a “food first” approach. As Roberts puts it, “A vitamin C tablet just provides vitamin C, whereas a portion of beetroot provides vitamin C, nitrates, potassium, manganese, fibre, folate . . .” However, there are some nutrients that are hard to get from diet alone. These include vitamin D3 (aim for 10ug a day, in winter), EPA and DHA fatty acids, unless you’re eating plenty of oily fish (store these in the fridge, as light and heat degrades them), and vitamin B12 for vegans.

Meanwhile, there are supplements that might be useful for athletes, including creatine for muscle mass and strength, and nitrates for aerobic performance. Even the most well-balanced eating plan can be optimised.

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Despite all the talk about “burning”, “incinerating” and “torching”, your metabolism is not a furnace. You won’t stoke it with hourly kindling and smother it with a hunk of wood. Multiple analyses and reviews conclude that meal frequency will make little difference to your metabolic rate. What you eat matters more. Meanwhile, a Japanese study noted that fasting provokes “a metabolically active state”. Put that in your furnace and smoke it.

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Detox from what? In 2009, an investigation of 10 detox companies by independent research body Examine found that none of them could name any of the toxins they purported to eliminate. Things have not improved in the decade since.

“The phrase ‘detoxing’ is overused,” says Grant. “Though I don’t disagree that we’re exposed to more toxins than ever, cutting out sugar, dairy and so on isn’t what I would class as a detox.”

Avoiding foods that are causing you digestive issues (potentially, but not always, including the aforementioned groups) will support your body’s detoxification process. “But a calorie deficit has the potential to increase toxin exposure, as some toxins may be stored up in fat cells,” cautions Grant. Instead, he advises increasing your intake of high-nutrient whole foods and digestion-boosting fibre, while adding the occasional sauna session to your gym schedule. 

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