5 popular fad diets: The experts opinion

People are always after the fastest way to lose weight, but are these diets sustainable in the long run? We speak to trained dietician and chef, Clare Gray, to find out more.

The media promote a certain type of ‘ideal’ body image which makes many feel that they have to look a certain way in order to be seen as attractive.

Having a smaller waist, a bigger bum, a thigh gap and thinner legs are all amongst the goals that women aim to achieve.

Alternatively, many men believe that they need to be masculine, muscly, physically strong and have a good physique to be desirable.

Clare Gray, courtesy of her Twitter.

Fad diets promise quick weight loss or other inviting health benefits and often include restricting certain food groups, yet there is very little evidence of any long term success from following these plans.

Here is a breakdown of five popular fad diets including the positives and negatives of following them with close reference to trained chef Clare Gray, who is also a registered dietitian in the UK and USA.

1. The Atkins diet

Eating less carbs and lots of protein is key to achieve results from the Atkins diet. Credit: pexels

The Atkins diet involves consuming more protein rich foods such as chicken, pork and beef, and restraining from products containing carbohydrates including fruit, vegetables and whole grains. Positives of following this diet include significant weight loss.

A lot of fat is eaten when following this diet, especially saturated fat, due to the vast consumption of animal products which can, in turn (according to a recent study), increase your cholesterol levels leading to a higher chance of heart failure.


‘It is incredibly unbalanced, low in fibre and low in important vitamins, minerals and phytochemicals.

‘High protein diets can also have detrimental consequences for renal function. Carbohydrates are important for blood glucose regulation.

‘Common side effects of the diet are constipation, lethargy and bad breath (related to the production of ketone bodies). It is unsustainable and harmful.’

2. The Alkaline diet

Eating lots of fruit and veg is key to the alkaline diet.

The Alkaline diet works on the belief that foods which cause an acidifying affect in the body once broken down such as meat, fish, dairy, pasta and bread should be avoided and foods which cause an alkalising affect in the body such as fruits (surprisingly including lemons), vegetables, green tea and apple cider vinegar should all be consumed. The idea is that by doing this, the body’s PH level remains between 7.3 – 7.4, weight will be lost and overall health, improved.


‘There is lots of contradictory information written about this diet. Some sources of information claim a food is acid producing where as others claim it is an alkaline food.

‘The basic principles of this diet is actually in line with typical healthy eating advice. The scientific principle behind this diet is utterly flawed.

‘The body has a number of homeostatic systems in place to ensure that the pH of the blood is tightly maintained, for example, sodium bicarbonate is secreted if the pH of the blood is too low whereas CO2, excreted through respiration is used to remove acid from our blood stream.

‘I wouldn’t advocate this diet, its confusing and unnecessarily complicated and again it is potentially unbalanced – meat, fish (especially oil fish) and dairy provide important nutrients and are part of a healthy balanced diet.’ 

3. The Juice Cleanse diet

Vegetable juices are better for you than fruit juices as they contain less sugar. Credit: pexels

The Juice Cleanse diet aims to eliminate all solid foods and replace them with fruit and vegetable juices from any time period between three days to a few weeks.

Juicing has become increasingly popular over the last couple of years, especially after a documentary called ‘Fat, Sick and Nearly Dead’ in which Joe Cross, an overweight man with a number of health conditions, took on the juice cleanse for 60 full days. He went from 140kg to 95kg and his overall health improved.

This post shows Joe at the start of his juice cleanse (left) and at the end of the 60 days (right). Picture courtesy of Instagram.


‘Juice cleansing is completely unbalanced, unsustainable and expensive.

‘Fruit juices are very high in sugar (a typical glass of orange juice contains 4-6 oranges, you would not comfortably consume that quantity of fruit within one sitting). Vegetable juices are better as they are naturally lower in sugar.

‘All of the fibre is removed through juicing which is really important to help us feel fuller and to maintain our gut health. Using juices as a meal substitute is extremely unhealthy and unnecessary.’

4. The Paleo diet

People following the Paleo diet also believe in natural oils such as coconut oil and natural sweeteners like maple syrup.

The Paleo diet aims to reduce processed items by sticking mainly to the foods eaten by humans in the Paleolithic era.

This diet is sometimes compared to Atkins as it too involves the consumption of protein. Grains, legumes and dairy is not allowed. Nuts and seeds are recommended in moderation, and the growing trend of fermented foods such as sauerkraut and kimchi come in to play with this diet.

The idea of following it is that it results in weight loss, arguably down to the restriction of certain foods. Furthermore, the consumption of more protein leads to feeling fuller for longer.


‘Although it’s less restrictive than Atkins, it is still an unbalanced diet – it’s unadvisable to cut out dairy foods unless there is a specific medical reason to do so. Dairy foods contain important nutrients, in particular calcium. As I mentioned with Atkins, high protein diets such as this can have negative implications for renal function. I wouldn’t advocate this diet.’

5. The 5:2 diet

The 5:2 diet includes five days of eating normally vs. 2 days of fasting.

The idea of the 5:2 diet is to eat freely for five days of the week, and fast for the remaining two – only intaking 500 calories a day for women and 600 for men on these days.

The pros to this diet include eating whatever you want, within reason, for most of the week. However by doing this, on the two days where only a small proportion of the daily recommended calorie intake is being had, energy levels are low and key nutrients are missed out on.


‘Dieting intervenes with our innate hunger and fullness cues. Intentionally restricting so significantly for 2 days of the week, rather than eating in attainment with our bodies requirements, will undoubtedly disrupt our internal satiation and hunger signals. As with all diets this is likely to lead to food fixation and preoccupations, feelings of guilt and shame if you “cheat” etc. This is another example of an unsustainable diet.’


The latest statistics released by Mintel on eating habits show that half of Brits have tried to lose weight in the last year. Two thirds of these people are on a diet most or all of the time.

Helen West, a postgraduate administrator at Kent University, has tried a variety of diets but has found that Slimming World, where she is now a consultant (in Herne Bay), is the most sustainable way of eating.

In this piece of audio, Helen talks about her reasons for choosing to diet, the benefits and drawbacks of following the Atkins diet and the problem with most fad diets.

Aisla Sargent, naturopathic nutritional therapist, tells Food For Thought why she doesn’t condone fad dieting and explains why a healthy balanced diet is essential.

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