In short: Most weight loss myths promise shortcuts: cut out a food group, skip meals, take a supplement or target one body part. The evidence points the other way. Sustainable weight loss comes from a modest, consistent reduction in calories, a balanced diet you can keep to, regular activity, good sleep and, for some people, medical support after a proper assessment.

This guide, written by a Ready Health prescribing pharmacist in Standish, looks at ten common myths and what UK health guidance actually says.

Myth 1: Do extreme or crash diets give the best results?

The reality: very restrictive diets can produce fast early weight loss, much of it water, but they are hard to sustain and often lead to regain. They can also leave you short of nutrients and feeling tired. Very low calorie diets (around 800 calories a day or fewer) should only be followed with clinical supervision. For most people, a modest daily deficit alongside a balanced diet works better over time. The NHS suggests aiming to lose around 0.5 to 1kg a week.

Myth 2: Are carbs the enemy?

The reality: carbohydrates are not fattening in themselves. Wholegrain bread, oats, potatoes with skins, beans and lentils provide fibre that keeps you full and supports gut health. Starchy foods should make up just over a third of what you eat, according to the NHS Eatwell Guide. The things worth cutting down on are sugary drinks, sweets, pastries and refined snacks.

Myth 3: Does eating fat make you fat?

The reality: fat is energy-dense, so portion sizes matter, but some fat is essential. Unsaturated fats from oily fish, nuts, seeds and olive or rapeseed oil support heart health. Low-fat processed products are not automatically healthier, as they can be high in sugar or salt.

Myth 4: Are weight loss supplements the key?

The reality: most over-the-counter "fat burners", detox teas and slimming pills have little good evidence behind them, and some sold online have been found to contain undeclared or dangerous ingredients. Never buy weight loss medicines from unregulated websites or social media sellers. Licensed weight loss medicines exist, but they are prescription-only and are only suitable for some people after a clinical assessment.

Myth 5: Does skipping meals help you lose weight?

The reality: skipping meals often leads to feeling very hungry later and making less healthy choices. Some people do well with structured eating windows, but a regular pattern of balanced meals suits many others better. What matters most is your overall intake across the day and week.

Myth 6: Does eating late at night cause weight gain?

The reality: the clock matters less than what and how much you eat in total. Late-night eating can be a problem if it means extra snacks on top of your usual meals or if it disturbs your sleep, but a balanced evening meal is not a cause of weight gain in itself.

Myth 7: Are all calories the same?

The reality: for weight change, energy balance is what counts, but food quality affects how full you feel and your long-term health. Protein and fibre-rich foods help control hunger, while sugary drinks and ultra-processed snacks are easy to over-consume. Think of both quantity and quality.

Myth 8: Is exercise more important than diet?

The reality: both matter, in different ways. Changes to eating usually drive most of the weight loss, while physical activity helps maintain weight loss, protect muscle and improve heart health, mood and sleep. UK guidance recommends at least 150 minutes of moderate activity a week plus strength exercises on two days.

Myth 9: Can you target fat loss from one area?

The reality: doing endless sit-ups will strengthen your core but will not specifically burn fat from your tummy. Fat loss happens across the body, in a pattern largely determined by genetics and hormones. A reduction in waist size is, however, a good sign that harmful internal fat is falling.

Myth 10: Should weight loss be steady every week?

The reality: weight naturally goes up and down from day to day because of fluid, salt, hormones and digestion. Plateaus are normal. Look at the trend over several weeks, and track other measures such as waist size, energy, sleep and how your clothes fit.

Bonus myth: Are weight loss medicines a quick fix?

The reality: prescription weight loss medicines can help some adults living with obesity or weight-related health conditions, but they are not suitable for everyone, can cause side effects, and work best alongside changes to diet and activity. Weight is often regained after stopping. A prescriber will assess your medical history, current medicines and goals before deciding whether any treatment is appropriate.

Frequently asked questions

How much weight is safe to lose each week?

For most adults, around 0.5 to 1kg (1 to 2lb) a week is a realistic and safe target.

Do I need to cut out sugar completely?

No, but cutting down on free sugars, such as those in sugary drinks, sweets and biscuits, is one of the easiest ways to reduce calories.

Why have I stopped losing weight?

Plateaus are common as your body adjusts. Reviewing portion sizes, activity, sleep and stress usually helps. If you are worried, a clinician can check for medical factors.

Are online weight loss pills safe?

Only buy medicines from a registered UK pharmacy or prescriber. Products from unregulated sellers may be fake or contain harmful ingredients.

Key takeaways

There is no shortcut: modest, consistent changes beat extreme diets.
No single food group needs to be banned; focus on quality and portions.
Supplements and detox products rarely work and can be unsafe.
Activity, sleep and support all help you keep weight off.
Medical treatment can help some people, but only after a proper clinical assessment.

Sources and further reading

Last reviewed: October 2026 by Shamir Patel, Independent Prescribing Pharmacist, Ready Health. This article is general information and does not replace advice from your own clinician.

If you are in Standish, Wigan, Chorley or nearby and want help separating fact from fiction, book a weight management consultation at Ready Health. We will look at your health and goals and help you build a plan based on evidence.

10 Common Weight Loss Myths, Debunked by a Pharmacist