Fad diets through the decades - the good, the bad and the terrifying

Weight Watchers has been practically synonymous with dieting for decades. Lampooned in Little Britain as ‘Fat Fighters’ – where ghastly group leader Marjorie shamed members at weigh ins – in reality, the brand has endorsed sensible calorie-controlled eating and gathered an army of devotees since it began as a support group for overweight New Yorkers in 1963.

At its peak more than two million people in the UK used Weight Watchers every year and the NHS handed over millions of pounds to the organisation to help its patients lose weight.

But this month Weight Watchers hit the headlines for a different reason after filling for bankruptcy.

How could a diet juggernaut, with former ambassadors including Oprah Winfrey and Robbie Williams, find itself £860m in debt? Weight-loss jabs will no doubt have contributed to its financial woes.

Will weight-loss drugs mean the end of traditional diets?

Dietician Dr Linia Patel says, “GLP-1 medications like Ozempic and Mounjaro are certainly reshaping the weight-loss landscape. They work! Particularly for people with obesity or related metabolic conditions.”

So, have fat jabs heralded the end of the traditional diet? No, says Dr Patel author of Food for Menopause. “They are not a one-size-fits-all solution or intended as casual weight-loss tools. They don’t replace the need for sustainable, behaviour-driven changes. Medications can help take the ‘food noise’ away, but they don’t teach you how to eat well for life. 

“Traditional diets – especially those supported by qualified health professionals – aren’t obsolete. Ideally, medical therapy coupled with nutrition, movement, mindset and lifestyle coaching will be the way forward.”

Fat jabs can cause side effects like nausea, constipation and muscle loss, and the new oral GLP-1 pills, such as orforglipron, which could be on the market as early as next year, are being welcomed with caution.

Dr Patel says, “The convenience of a daily pill could widen access and is an alternative for those uncomfortable with needles, but it may also lead to over-prescription or misuse.”

7 fad diets and what science says about them now

Before these jabs there was a relentless queue of fad diets competing with Weight Watchers.

Bini Suresh, British Dietetic Association spokesperson and head of dietetics at Cleveland Clinic London, gives us her expert view.

1. The Grapefruit Diet 

Popularity peak

In the late 1970s, we hot brushed our Farrah Fawcett hair flicks, pulled on our flares and legged it to Tesco to clear the shelves of grapefruits. Brooke Shields endorsed their slimming properties, and we all wanted her body (and eyebrows).

What was it?

Eating half a grapefruit before every meal apparently unlocked its ‘fat-burning enzymes’. Your eye-watering citrus chaser was followed by a meagre 800 calorie of high-protein, high-fat meals a day. At least there was no chance of developing scurvy.

What does science say about it now?

Suresh says: “While a study indicated that participants who ate half a grapefruit before meals experienced modest weight loss and improved insulin resistance, the process is unclear.

"Moreover, grapefruit can interact with certain medications, including statins and antihypertensives, potentially leading to adverse effects. Not recommended.”

2. The Cabbage Soup Diet

Popularity peak

Remember the crumpled, photocopied piece of paper with the cabbage diet plan doing the rounds in the 1980s? It was pre-email, so that shared document was sacred.

If you made it through the entire week, you were a legend among friends, most of us were day three casualties.

What was it? 

Cabbage and vegetable soup, all day every day, for seven days. By day two, the smell alone would kill your appetite. The plan allowed scraps of solid food – on baked potato day, the heavens would open and angels sang.

What does science say about it now?

Suresh says: “This diet leads to rapid weight loss, primarily from water and muscle mass. It’s nutritionally unbalanced, low in protein and lacks essential vitamins and minerals.

"It could result in fatigue, bloating and rebound weight gain. Again, not recommended.”

3. The F-Plan Diet

Popularity peak

The F in F-plan stood for fibre and the mantra was feel fuller for longer. It was 1982, Princess Diana’s willowy figure was every girl’s dream, and spooning cereal into our hungry mouths to achieve it was alluring. 

What was it?

It was 1500 calories of fibre, carbs, low fat and sugar? a day, so think wholemeal bread, bran flakes and jacket potatoes. The F in F-Plan unofficially stood for flatulence…

What does science say about it now?

Suresh says: “This high-fibre approach can aid weight loss and cholesterol control, but it’s extreme for some and a sudden fibre increase may cause bloating and digestive discomfort.

"It’s important to build up fibre gradually and drink plenty of fluids.”

4. Rosemary Conley’s Hip and Thigh Diet

Popularity peak

Late 1980s, early 1990s. These were the days when we hid our behinds with cardigans – before everyone wanted ‘thick’ thighs and big booties – so the name spoke to us.

Rosemary’s perfectly coiffured blonde ’do was a regular feature on breakfast TV sofas, and her book sold 2 million copies.

What was it?

Resolutely low fat, and carbs were also welcome to the table. Nuts, butter and cheese (except the dreaded cottage cheese) were banished.

What does science say about it now?

Suresh says: “While it promotes exercise and encourages healthy eating, the concept of spot reduction [targeting fat loss in specific body areas] is unsupported by evidence. Also low in essential fats.”

5. The Atkins Diet

Popularity peak

This egg-and-meat-fest fad exploded around 2003, inspired by tiny and toned celebs Geri Halliwell and Jennifer Aniston. They kept quiet about the bad breath though.

What was it? 

Eating a diet of protein and fat was said to help turn fat into energy. Creator Robert Atkins proclaimed, “Carbohydrate is the bad guy” and we were only too happy to tuck into fried bacon and eggs for breakfast and pop two steaks for a mid-afternoon snack. 

What does science say about it now?

Suresh says: “Research indicates potential significant short-term weight loss. However, the high intake of saturated fats and reduced fibre can raise LDL cholesterol levels and affect gut health.

"May have adverse cardiovascular effects long term and not aligned with current UK dietary guidelines.”

6. The Caveman Diet

Popularity peak

It was 2013. Same-sex marriage was legalised, Prince George was born, and ITV celebrated 25 years of This Morning, in more innocent times before Phillip Schofield was cancelled and Ruth and Eamonn separated. 

What was it?

Based on what hunter-gatherers consumed millions of years ago – unprocessed meats, fish, eggs – the paleo plan claimed to improve health and maintain weight. Sugar, grains and dairy were out.

What does science say about it now?

Suresh says: “Some studies suggest benefits in weight loss and metabolic markers. However, may lead to nutrient deficiencies, particularly in calcium and vitamin D, increasing the risk of osteoporosis.

"It’s unnecessarily restrictive for most people.”

7. The 5:2 Diet 

Popularity peak

By 2020 aspirational stars such Beyonce and Benedict Cumberbatch were following The plan popularised by Dr Michael Mosely, so we dutifully followed suit. Then came lockdown and most of us swapped fasting for boozing.

What is it?

Drastically cutting calories on two days of the week, eating regularly for five. Then came other variations, such as the 16:8 diet, where you fast for 16 hours and eat within an eight-hour window. Yes, it seriously triggered our maths phobia too.

What does science say about it now?

Suresh says: “Studies show it can aid in weight loss and improve metabolic health. However, it's not suitable for everyone, including those with certain medical conditions so requires individualised assessment.

"Timing alone doesn’t guarantee a healthy diet; nutrient quality still matters.”