Fad diets explained: are soup-based diets healthy?

So, what do you need to know about single food diets like the soup diet? And are there ways to make them nutritious, filling and even tasty? (Short answer: if you’re sticking purely to one food item, then no.) But you can still include these foods as part of your wider menu. With insight from H&B nutritionist Millicent Chapman, we’ll learn the risks behind ‘fad’ diets, plus how to add filling and flavoursome sources of protein, fibre and carbs to any diet...

You might think: no calorie counting, no complicated macros – just soup for breakfast, lunch and dinner. But even if a Cream of Tomato for breakfast sounds tolerable, it’s still very easy to miss out on certain nutrients and food groups. It’s possible to pack soups with added sources of protein, carbs and healthy fats to keep them balanced but they still shouldn’t be your only meal.

Sometimes, it can be tempting to go to extreme lengths to meet your weight loss goals. But there’s almost never a safe way to lose weight in a matter of days. Any weight loss you do experience is likely to be water and muscle loss rather than fat loss, and you’ll probably gain it back once you return to a normal diet.^2,3 Plus, proper nutrition goes deeper than your body weight. If followed for a long time, restrictive diets could cause serious damage to your body including iron deficiency anaemia or osteoporosis.² 

“Diets that promise rapid results within a short timeframe should be approached with caution,” explains Millicent. “For example, the NHS recommends aiming for a gradual and sustainable weight loss of around one to two lbs per week.”

Soups are mainly made of veg – so they’re good for you, right? While vegetables are full of vitamins and minerals, they can’t provide adequate amounts of food groups like protein, fats and carbohydrates. Your body needs these to maintain proper muscle function, give you energy, support your cognitive function and more.

Even if you’re considered healthy, it’s important to follow proper weight management practices and we don’t recommend restrictive diets for anyone. “When aiming for weight loss, particular emphasis should be placed on adequate protein and fibre intake. Both nutrients support appetite regulation by promoting satiety (fullness). This should be combined with a calorie deficit, meaning energy intake is lower than energy expenditure,” explains Millicent. Restricting your nutrition can be extremely risky if you’re pregnant, you’re very physically active or you have a condition such as diabetes where you need to monitor your nutritional intake. In these cases, you should speak to your healthcare professional, such as your doctor or registered dietician, before trying any new diets.

You might feel motivated at first, but restricting your nutrition comes with unwanted side effects. Without the fuel to keep your body working, you’ll begin to feel very tired and you might also experience irritability and bad breath.² If you’re cutting out certain nutrients for longer periods, you might experience things like hair thinning, changes to your mood and concentration or becoming ill more often.^4-9 Depending on the foods you’re cutting out, your gut might also respond with constipation, gas or general digestive discomfort.²