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Do you want to finally lose weight? Have you tried a lot of things, but nothing works in the long term? Find out more here about nutrients, sensible diets and fasting to lose weight in a targeted and long-term way. Because only a long-term change in your lifestyle will really get you to your goal.

How to lose weight: what really counts

Body fat melts when the body uses more energy than it takes in. This energy balance is easy to misjudge: people who said they ate less than 1,200 kcal a day and still did not lose weight actually ate 47% more than they had written down. Why a diet stalls and which nutrients matter then is explained in the guide to the unsuccessful diet. The deficit should not be too radical. After a very large weight loss, the resting metabolic rate, meaning the energy the body burns at rest, was still around 700 kcal a day below the starting value six years later. Sleep counts as well: with 5.5 instead of 8.5 hours of sleep, dieters lost only 0.6 instead of 1.4 kg of fat in two weeks. Muscle is the strongest lever to boost the metabolism: protein raises the metabolic rate by 15 to 30% during digestion, and strength training increased the resting metabolic rate by about 96 kcal a day. If the scale goes up during a diet, it is usually water, because glycogen, the body's carbohydrate store, is held with three to four parts water (gaining weight despite fasting).

Diets and fasting: which way of eating helps with weight loss?

Intermittent fasting replaces calorie counting with fixed breaks from eating. The best known methods are 16:8 with a daily 16-hour break, 5:2 with two days of 500 to 600 kcal a week, and fasting every other day. In an analysis of 99 trials, every form lowered body weight compared with eating freely. The 16:8 method lowered body weight by 1.60 kg in a meta-analysis and was the best at preserving fat-free mass, which includes the muscles (16:8 intermittent fasting). How it differs from water fasting and sham fasting is covered in fasting in focus. On the keto diet, carbohydrates drop to no more than 50 g a day and the body switches from sugar to fat as its fuel; in 13 trials lasting at least twelve months, it brought more weight loss than a low-fat diet, with less hunger. Cutting sugar works quickly too: when children with obesity reduced sugar from 28% to 10% of their daily calories for nine days, triglycerides fell by 46% and body weight by 0.9 kg (10 days without sugar).

Belly fat, cravings and sleep: the most common hurdles

For health, waist circumference should be below 80 cm in women and below 94 cm in men; above 88 and 102 cm, the risk of cardiovascular disease rises. The most harmful is visceral fat, which lies deep in the abdomen around organs such as the liver, pancreas and heart, and every centimetre less around the waist lowers the risk of vascular disease by 3% (abdominal girth). A single problem area cannot be trained away, but a full-body workout, fibre and protein make the belly shrink along with total body fat. Constant sugar cravings often begin with the sweet products that are on offer everywhere, every day. Light in the bedroom matters as well: in a study in JAMA Internal Medicine, weight gain was greatest in people who slept with the light or the TV on (falling asleep in front of the TV). The gut plays a part too, because a change in the intestinal flora can contribute to weight gain; fibre, fermented foods and omega-3 fatty acids help to build up the intestinal flora.

Exercise and muscles: burning fat, keeping strength

The WHO recommends 150 to 300 minutes of moderate or 75 to 150 minutes of vigorous activity a week plus regular muscle-strengthening exercise; tips for getting started are collected in getting fitter. Interval training, the alternation of short, very intense efforts with recovery phases, significantly reduced total, abdominal and visceral fat in a meta-analysis of 39 studies, and one to two sessions a week with at least 48 hours of rest in between are enough. Functional training uses everyday movements such as pulling, pushing, squatting and carrying, mostly with body weight alone. Muscles need constant use: after just one week of strict bed rest, healthy young men had lost 1.4 kg of lean mass. Training each major muscle group at least twice a week and a protein intake of up to about 1.6 g per kilogram of body weight keep the muscles strong. It is never too late: adults aged 50 and over gained an average of 1.1 kg of lean body mass through strength training (age-related muscle loss). Even cold burns energy: two hours a day at 17 °C reduced body fat within six weeks, driven by brown fat (losing weight by freezing).

Nutrients and plant substances that support weight loss

Glucomannan, a dietary fibre from the konjac root, binds about 50 times its own mass in water, swells in the stomach and makes people feel full sooner; in 14 studies with 531 participants, body weight fell by 0.79 kg more than in the comparison groups. Green coffee bean extract reduces the absorption of sugar from food and lowered body weight by 1.23 kg and waist circumference by 1.00 cm in 15 trials with 897 participants. Both are presented together in the guide to glucomannan and green coffee. L-carnitine carries fatty acids into the mitochondria, the power plants of the cells, and lowered body weight by 1.21 kg and fat mass by 2.08 kg across 37 randomised trials, with about 2,000 mg a day giving the largest effect. In 81 overweight adults, R-alpha lipoic acid led to a greater drop in BMI than a placebo over 24 weeks, without any change in diet or exercise. Certain gut bacteria help as well: with Lactobacillus gasseri, people with a high share of abdominal fat lost 8.5% of their belly fat in twelve weeks (probiotics for weight loss).

All guides on weight loss and fitness at a glance

• Unsuccessful diet: why the scale stands still despite dieting and which nutrients support the metabolism.
• Metabolism booster: protein, strength training, water and sleep for a higher energy use.
• Intermittent fasting: 16:8, 5:2 and fasting every other day compared, with effects on weight and blood sugar.
• 16:8 intermittent fasting: how much weight the eating window removes and how it protects muscle.
• Keto diet: how ketosis works, what is allowed and how to get started.
• 10 days without sugar: what ten days with much less sugar change in the body.
• Abdominal girth: limit values, correct measuring and why visceral fat is so harmful.
• Interval training: burning fat with HIIT and Tabata in little time.
• Getting fitter: how much exercise is needed and which supplements help along the way.
• Age-related muscle loss: strength training and protein to build muscle at any age.
• Glucomannan and green coffee: feeling full and less sugar absorption, with intake and study results.
• L-carnitine: fat transport into the cells, dosage and studies on weight and endurance.

Frequently asked questions

What is the quickest way to lose weight?

The quickest lasting way is a moderate calorie deficit with unprocessed food, plenty of protein, exercise and enough sleep. Crash diets bring quick results on the scale, but after a very large weight loss the resting metabolic rate was still around 700 kcal a day lower six years later, and much of the weight had come back. A plan that can be kept up for months works faster in the end. More on unsuccessful diets.

Which food is good for weight loss?

Good choices are vegetables, pulses, whole grains, seeds, fruit and protein-rich foods, because fibre and protein keep people full for longer and protein raises the metabolic rate by 15 to 30% during digestion. Sugar and sweetened drinks should be reduced: nine days with much less sugar already lowered triglycerides and body weight in children with obesity. Foods with a low glycemic index led to small extra weight loss. More on boosting the metabolism.

How to lose weight without exercise?

Without exercise, weight loss depends entirely on the diet: eating less energy than the body uses, for example with fixed eating windows. In an analysis of 99 trials, every form of intermittent fasting lowered body weight compared with eating freely. Enough sleep supports this, as dieters with 5.5 instead of 8.5 hours of sleep lost less than half as much fat. Muscle is lost faster without training, though. More on intermittent fasting.

Why am I not losing weight?

The most common reason is that more is eaten than assumed: in one study, dieters who did not lose weight ate 47% more than they had recorded. Short sleep, an adapted metabolism after earlier crash diets, an underactive thyroid or certain medicines can also stand in the way; thyroid and medication should be checked by a doctor. A lack of nutrients such as magnesium or vitamin C can slow fat burning as well. More on unsuccessful diets.

How do I lose belly fat?

Belly fat cannot be trained away in one spot, but it shrinks along with total body fat. A full-body workout and interval training help: in 39 studies, HIIT significantly reduced abdominal and visceral fat. Fibre and protein in the diet, less alcohol and sugar, enough sleep and less stress support the process. Every centimetre less around the waist lowers the risk of vascular disease by 3%. More on abdominal girth.

How to stop cravings when dieting?

Cravings are often driven by blood sugar swings and strong restriction, for example skipped meals. Fibre-rich food and protein keep blood sugar steadier. Glucomannan from the konjac root swells in the stomach and makes people feel full sooner, and in 14 studies body weight fell by 0.79 kg more than without it. Cutting sugar can bring cravings in the first days, and the sense of taste adjusts over several weeks. More on glucomannan and green coffee.