By Ellen Manning
From paleo to ketogenic, our expert reveals the pros and cons of some of the best-known diets out there.
Every week seems to bring about a new diet promising a magic solution when it comes to weight loss. But do they actually work? Seven asked Polly Hale, nutritionist and weight loss coach at The Fit Mum Formula, for her thoughts on some of the diet trends out there at the moment.
1. Low carb
Reducing carbohydrates means cutting out rice, potatoes and pasta, as well as dairy and fruit. “It’s thought that reducing carbohydrates helps to balance blood sugar and therefore energy levels,” says Polly, “as well as keeping hunger to a minimum”.
Pros: You can eat a filling diet without over-consuming calories. It’s also simple so makes meal planning easier.
Cons: Going low carb doesn’t work for everyone and some people don’t feel great without enough carbs. And while you can make and buy low-carb treats, traditional sugary snacks are off-limits, which can lead to blow-outs and binges.
Paleo basically means eating like our ancestors – cutting out grains, dairy, legumes, alcohol and processed foods.
Pros: Cutting out processed foods and focusing on whole, natural, nutrient-dense foods makes this a nutritious way of eating, while some people will also benefit from reducing dairy and gluten.
Cons: The types of food may be restricted, but the overall quantity and proportions of fat, carbohydrate and protein are vague, so you won’t necessarily be getting the right balance of macronutrients. It’s also easy to under-eat, says Polly, and you could be cutting out some “banned” foods unnecessarily, losing their potential health benefits.
Whole30 is similar to Paleo but also cuts out natural sugars like honey.
Pros: “The foods you're allowed to eat are very nutritious and, so long as you're getting a good variety, you'd get all the nutrients you need,” Polly says.
Cons: Avoiding whole food groups like dairy, grains and legumes could leave a person deficient in certain nutrients. “Cutting out all treats completely is also unsustainable for most people and may even lead to bingeing on ‘forbidden’ foods, or orthorexia – a fear of ‘unhealthy’ foods,” Polly adds.
4. 5:2 Diet
This form of intermittent fasting means consuming 500-600 calories two days a week, with a “normal” diet of 2,000-2,400 calories on the other five days, effectively creating a calorie deficit across the week.
Pros: As well as weight loss, results can include improved blood pressure and cholesterol profile. It could also help you to learn to go for longer without eating, says Polly, so in the long run you might be less inclined to snack.
Cons: The drastic drop to 500 calories a day can cause hunger, low energy and poor concentration, says Polly. “Women tend to fare worse with intermittent fasting as our hormones stay better balanced when we don’t go too long without eating.”
5. Meal Replacement Plans
Plans like Slim Fast and Lighter Life see meals replaced by calorie-restricted products including shakes, soups and bars.
Pros: For some people, the convenience of a readymade product is appealing, meaning there’s no need for cooking, preparing or calorie-counting, says Polly.
Cons: Polly says: “Pre-made foods will never match up nutritionally to fresh, whole, natural foods, especially when many of these products use cheap ingredients and bulking agents.” Sticking to the same products day-in, day-out can also lead to “flavour fatigue”.
A ketogenic diet forces the body to switch its fuel supply to run almost entirely on fat. When the body is in “ketosis”, insulin levels become very low and fat burning increases, helping you lose weight.
Pros: Some people find the diet really satiating, says Polly, and the lack of sugar and carbs can help get erratic blood sugar under control.
Cons: “Getting into ketosis means cutting out even healthy foods like fruit and many vegetables, so it's very nutrient deficient”, Polly says. “The science behind keto being good for everyone isn't very sound – in fact, the only place it seems to really be beneficial is in epilepsy sufferers.”
7. Intermittent Fasting
As its name suggests, intermittent fasting involves fasting for certain periods of time, though the timings can be varied.
Pros: Intermittent fasting can help get someone back in touch with their natural appetite by realising they didn't need food at certain times and were eating out of habit, says Polly. “Limiting eating times tends to limit calorie intake by default, so it can be helpful for weight loss.”
Cons: “In some people it simply leads to low energy, poor concentration, and making up by eating way more later,” Polly says. Like keto, the science behind intermittent being great for your body and brain health is mixed. “There's no solid reason to recommend skipping meals if it doesn't suit someone,” Polly adds.
How can I diet safely?
Sticking to any form of “diet” long term has to be enjoyable. Polly says: “As well as keeping you feeling, looking and performing at your best, whatever that means to you, it has to fit to your lifestyle in a convenient and not too disruptive way.” Temporary diets can work to kickstart weight loss, but the key is knowing how to eat healthily once you reach the end of the plan. “Unfortunately that’s where short term diets fall down,” Polly says. “They don’t teach long term habits and strategies for health.”