Diet questions
Are online diet plans safe?
Some are, some aren't. A plan built on ordinary food, a modest calorie cut and clear advice on who should avoid it is usually safe for healthy adults. Be wary of plans that promise fast results, push supplements or shakes, or set very low calorie targets without medical supervision.
What makes a plan risky
Most of the harm from online plans comes from a few patterns:
- Very low calorie targets. Diets of around 800 kcal a day or less should only be done with medical supervision. They can cause gallstones, dizziness and muscle loss.
- Supplements and "fat burners". In the US the FDA does not approve dietary supplements before they go on sale, and it has found weight-loss products with hidden drug ingredients.
- Cutting whole food groups for no clear reason. Dropping all grains, dairy and fruit at once makes it hard to get enough fibre, calcium and vitamins.
- No medical warnings. A good plan tells you who should check with a doctor first. A plan that says it suits everyone is a warning sign.
A 10-point safety checklist
- Is the author named, and do they have real training, such as a registered dietitian or doctor?
- Does it use normal food you can buy at a supermarket?
- Is the target weight loss around 0.5 to 1 kg (1 to 2 lb) a week, not "10 pounds in 10 days"?
- Does it tell you who should not follow it, such as people who are pregnant, have diabetes or have had an eating disorder?
- Is the full price clear, including any subscription that renews automatically?
- Does it work without buying its own products?
- Does it link to evidence, not just before-and-after photos?
- Does it include plenty of vegetables, fruit, protein and fibre?
- Is there a plan for what happens after the first month?
- Does its privacy policy say what happens to your weight, health and food data?
A plan that passes eight or more is probably a reasonable place to start. Three or more "no" answers is a good reason to keep looking.
A note on apps and your data
Food-tracking and diet apps often collect your weight, meals, photos and sometimes your location. In the US, many of these apps are not covered by HIPAA, the health privacy law that applies to your doctor. Read what the app shares with advertisers, and turn off anything you don't need.
Safer and riskier, at a glance
| Usually fine | Be careful |
|---|---|
| Mediterranean or DASH meal plans | Juice cleanses and detox teas |
| Calorie or food trackers used loosely | Shake-only plans without medical support |
| Recipe-based plans from qualified authors | Plans that need injections, drops or pills they sell |
Related questions
Are meal-replacement shakes safe?
Used for one meal a day as part of a balanced diet, they are generally fine for healthy adults. Shake-only plans that are very low in calories should be done with medical supervision.
Are free diet plans worse than paid ones?
Not necessarily. Free guidance from sources like the NHS or the Dietary Guidelines for Americans is solid. A high price doesn't mean better evidence.
What should I do if a plan makes me feel unwell?
Stop, eat normally, and talk to your doctor if symptoms like dizziness, palpitations or fainting don't settle quickly.
Keep reading
See how to spot a fad diet, when to see a dietitian and the full guide to choosing a safe weight-loss program. You can also read how diets are reviewed and the medical disclaimer.