“There was also the tin opener diet, which involved restricting yourself to tinned fruit and tinned meat and eating absolutely no carbohydrates,” she says.

There’s also the dreaded cabbage soup diet, which involves eating solely cabbage food for 10 days, though some interpretations allow a few other foods, such as fruit and dairy. The origins of this diet are unclear but it gained popularity in the 1980s and has resurfaced on TikTok more recently.

Why it causes fat loss

Restricting food intake to a single item or food group is likely to result in short-term weight loss, as people are limited in what they can eat and typically consume less, says Pearson.

“Diets like this become popular because, in theory, they’re easy to stick to,” she says. “The idea of simply eating one type of food is easier than learning the rules of a more complex diet plan.”

What we can learn from it now

“These single-ingredient diets are generally based on healthy foods,” so the foods they involve eating can be incorporated into a healthy diet, Pearson notes.

For example, “we could recommend eating a bowl of cabbage soup as a starter – it can be an excellent starter for weight management as it’s low in calories but high in fibre, helping you feel fuller before the main meal.”

However, don’t try following a one-ingredient diet, she says. They are so restrictive that they will lead to nutrient deficiencies if followed for weeks or months, as they’re not a source of all of the essential nutrients that the body needs to function, Pearson warns.

Additionally, a one-ingredient diet will lead to muscle loss, as well as fat loss, which slows down the metabolism as the body adapts to consuming less food. “This makes weight loss harder to sustain and increases the risk of weight regain,” she explains.

“Most people would find such diets very challenging to maintain for any length of time,” she says. “Weight loss is healthier, more effective and sustainable when it results from a balanced diet rather than an emphasis on isolated ingredients,” she says.

The air hostess diet

History

“In the 1960s, the air hostess job was seen as a glamorous choice for women, and everyone knew that airlines were highly selective regarding body shapes and attractiveness,” Dr Wilks-Heeg explains. “Being an air hostess was believed to provide the opportunity to meet wealthy men who could afford to travel, such as pilots or business travellers.”

As a result, Woman’s Own published the air hostess diet in 1969, for women who were aspiring to achieve a similarly svelte figure.

It involved eating a single hard boiled egg for breakfast, followed by a leafy salad with a glass of milk for lunch. Dinner was a 85g portion of lean meat (around half a chicken breast) with another leafy salad, amounting to a miniscule 354 calories per day.

Why it causes fat loss

“Inevitably, eating so few calories will result in weight loss,” Pearson says. “However, this is likely to be muscle loss as well as fat loss, which will compromise health and long-term weight maintenance,” she notes.

Such a low intake can also disrupt hormone balance, which can affect women’s menstrual cycles and reproductive health, Pearson explains. As with other low-calorie diets, it also risks causing nutrient deficiencies and is difficult to maintain.

What we can learn from it now

Eating 350 calories a day is “much too low to maintain for any sustained period of time”, says Pearson. However, the foods in the air hostess diet, when consumed in larger portions, can form the basis of a balanced diet that leads to weight loss, she says.

For example, eggs are nutrient-dense and full of protein, which will help to curb hunger pangs and cravings – though people should eat three to four for breakfast instead of one, she says. Meanwhile, meat contains essential amino acids that support muscle maintenance, she notes.