A fad diet is an eating plan that promises rapid weight loss through rules that sound scientific but are not supported by evidence. Think juice cleanses, the GM diet, or cutting entire food groups overnight. Fad diets do produce fast early results, yet research shows most dieters regain the weight, and studies of long-term outcomes find one to two thirds regain more than they lost.
How Do You Recognise a Fad Diet?
After two decades of watching diet trends come and go, I can tell you they all share the same fingerprints. If a plan ticks two or more of these boxes, be sceptical.
- Promises more than 1 kg of loss per week without medical supervision
- Bans an entire food group (carbs, fruit, dairy, cooked food)
- Sells a “detox” or “cleanse” your liver and kidneys already perform free of charge
- Relies on testimonials and before-after photos instead of published research
- Requires buying special powders, teas, or supplements to work
- Has a hard end date, like “lose 5 kg in 7 days”
Why Do Fad Diets Work at First and Then Fail?
The early drop is mostly water. Cutting carbohydrates empties glycogen stores, and every gram of glycogen holds about 3 g of water, so 2 to 3 kg can vanish in the first week without a gram of fat lost.
Then biology pushes back. Extreme restriction raises the hunger hormone ghrelin, lowers leptin, and burns muscle along with fat. When the diet ends, appetite returns to a body with a slower metabolism, and the regain cycle begins. This repeated loss and regain, called weight cycling, is linked in research to poorer cardiovascular health than stable weight.
What Do Popular Fad Diets Actually Deliver?
| The claim | What the evidence says |
|---|---|
| “Detox juices flush out toxins” | No clinical trial has shown juice cleanses remove any toxin; your liver and kidneys do this continuously |
| “Lose 5 kg in 7 days with the GM diet” | Early loss is water and muscle; there is no published research validating the GM diet |
| “Carbs are the enemy” | The JAMA DIETFITS trial of 609 adults found low-carb and low-fat diets produced nearly identical loss over 12 months |
| “This tea melts belly fat” | No food or drink targets fat in one body area; spot reduction has been repeatedly disproven |
What Should You Do Instead of a Fad Diet?
- Create a moderate energy gap. A 300 to 500 calorie caloric deficit loses fat at a pace your hormones tolerate.
- Keep every food group. The American Heart Association pattern, like traditional Indian thali eating, includes grains, dals, vegetables, fruit, and dairy.
- Anchor meals in protein and fibre. These two nutrients control hunger better than any rule about timing or food combining.
- Judge a diet by year one, not week one. Ask: can I eat this way at a wedding, on holiday, at 60? If not, the result is temporary. See my guide to what a healthy weight really is.
Frequently Asked Questions
Why do fad diets keep coming back with new names?
Because they sell hope on a deadline. The cabbage soup diet of the 1980s, the GM diet of the 2000s, and today’s 7-day detox are the same formula: severe restriction, fast water loss, inevitable regain, and a new customer for the next trend.
Are all popular diets fads?
No. The Mediterranean pattern and sensible low-carb or vegetarian plans have solid research behind them. The difference is that evidence-based diets set a sustainable calorie level, keep protein adequate, and have no expiry date.
I lost weight on a crash diet before. Why not repeat it?
Each cycle trades muscle for fat regain. Women who crash diet repeatedly through their 40s often arrive at menopause with less muscle and a slower metabolism, making every future attempt harder.
How much weight loss per week is realistic?
0.25 to 0.5 kg of true fat loss per week is what a sustainable plan delivers. Anything advertising much faster results is selling water loss dressed up as fat loss.
About the Author
Nidhi Kakar is a nutritionist and the founder of Art of Wellness. She specialises in women’s health through the midlife years, from the mid-30s to the mid-60s, and has guided hundreds of women through perimenopause, menopause, and post-menopause with personalised nutrition and lifestyle plans.
This article is for educational purposes and does not replace personalised medical advice.
