Fad diets explained
If you want to lose weight or eat more healthily you might be tempted to try a new diet. There are lots of trendy diets that appear in the news or are recommended by a friend. But is a ‘fad diet’ really the best way to lose weight? And what are the alternatives? Here I talk about some well-known fad diets and whether they can help you eat more healthily.
What is a fad diet?
There isn’t an official definition of a fad diet, but they tend be diets that you follow for a short amount of time. They usually claim to help you lose weight. Fad diets tend to go in and out of fashion, and there have been many different ones over the years. They’re often endorsed by celebrities or promoted on social media.
Will cutting carbs make me lose weight?
You might have heard of people reducing the amount of amount of carbohydrates they eat in order to try and lose weight. This is often called a ‘low carb’ diet. Famous low carb diets include:
- the Atkins diet
- the Dukan diet
- the ketogenic diet
- the fast 800
Your body’s main energy source is carbohydrates. The idea behind low-carb diets is that when you eat fewer carbohydrate foods your body starts burning fat for energy, causing you to lose weight.
There is some evidence to suggest that low carb diets can help you lose slightly more weight than low fat diets. If you’re somebody who wants to cut down the amount of less nutritious carbohydrate foods you eat, this diet may help you to do that.
But if you follow a low carb diet you might also find you eat fewer fruits, vegetables, and wholegrains. This can reduce the amount of vitamins , minerals, and fibre in your diet. Some people also experience unpleasant side-effects from low carb diets, including:
- constipation
- bad breath
- feeling tired and weak
There isn’t a lot of evidence about how safe it is to eat a low carb diet long term. You might also find it harder to stick to a restrictive diet like this for a long time.
Many people find it easier to focus on eating healthy complex carbohydrates in moderate portions. These include jumbo oats, sweet potatoes, sourdough bread, and brown rice and pasta.
Should I cut out specific foods?
You may also have heard of people removing certain foods from their diets. They may cut out grains, vegetables, or anything with a low pH (acidic foods).
These diets may be unhealthy as they might not have enough key nutrients and fibre. There is usually not a strong evidence base for these diets, but they are often promoted online. Well-known examples include:
- the paleo diet
- the carnivore diet
- the alkaline diet
- blood type diets
These diets can be very restrictive and difficult to follow. Instead, reducing ultra processed foods, and focusing on a balanced, nutrient dense diet can help you to meet both your weight loss and health goals.
Is fasting a good way to lose weight?
Intermittent fasting has become increasingly popular over recent years. You might have heard of:
- the 5:2 diet
- the 16/8 method
- the fast 800
For some people, intermittent fasting can help with weight loss – as it results in reduced overall calorie intake. For others, people can overcompensate for fasting periods by eating more during eating windows.
What is the healthiest way to lose weight?
The healthiest way to lose weight is to follow a sustainable, balanced way of eating. Diets only tend to work in the short term because:
- they are hard to stick to
- the body adapts to low calorie intake so you may hit a plateau
Instead, if you want to lose weight it’s healthier to reduce calories by 500 to 600 per day while following a balanced diet such as the Mediterranean diet. You could remove 500 to 600 calories per day by:
- cutting out ultra processed snacks
- drinking less alcohol
- including more fibre and protein in your diet to keep you full and prevent overeating
You don’t need to cut out any core food group to lose weight, instead focus on nutrient density and modest portion sizes, in addition to an active and healthy lifestyle.
You can’t predict when you might want to see a GP, but you can be ready for when you do. Our GP subscriptions are available to anyone over 18 and give you peace of mind, with 15-minute appointments when it suits you at no extra cost.
-
Sources Sources
- Fad Diets. British Dietetic Association. bda.uk.com reviewed September 2024
- The Fast 800. thefast800.com accessed February 2025
- Obesity. Oxford Handbook of Nutrition and Dietetics (3 edition). Oxford Medicine. oxfordmedicine.com, April 2020
- Low Carb. Diabetes UK. diabetes.co.uk updated January 2024
- Healthy Eating. British Dietetic Association. Bda.uk.com, reviewed September 2024
- Rosenbaum M, Leibel RL. Adaptive thermogenesis in humans. Int J Obes (Lond). 2010;34 Suppl 1(0 1):S47-55. doi: 10.1038/ijo.2010.184
- The Mediterranean diet is a healthy diet – but it is not the only way to eat healthily. British association of dietitians. Bda.co.uk, accessed March 2025
About our health information
At Bupa we produce a wealth of free health information for you and your family. This is because we believe that trustworthy information is essential in helping you make better decisions about your health and wellbeing.
Our information has been awarded the PIF TICK for trustworthy health information. It also follows the principles of the The Information Standard.
More diet and nutrition articles
Did you find our advice helpful?
We’d love to hear what you think. Our short survey takes just a few minutes to complete and helps us to keep improving our healthy lifestyle articles.
Legal disclaimer
This information was published by Bupa's Health Content Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals and deemed accurate on the date of review. Photos are only for illustrative purposes and do not reflect every presentation of a condition.
Any information about a treatment or procedure is generic, and does not necessarily describe that treatment or procedure as delivered by Bupa or its associated providers.
The information contained on this page and in any third party websites referred to on this page is not intended nor implied to be a substitute for professional medical advice nor is it intended to be for medical diagnosis or treatment. Third party websites are not owned or controlled by Bupa and any individual may be able to access and post messages on them. Bupa is not responsible for the content or availability of these third party websites. We do not accept advertising on this page.
