How to lose weight fast: Safe and effective strategies

There are many reasons you may wish to lose weight fast, like an upcoming holiday, a wedding or another event.

In this guide, you’ll learn about safe, evidence-based ways to lose weight faster, including diet strategies, exercise and medical treatments.

While it is possible to lose weight fast, we generally recommend taking a slower and more gradual approach to weight loss. This is widely recognised as being more sustainable and effective in the long run.

Medically reviewed by

Dr Kathryn Basford

Last reviewed: 26 Feb 2026

What's on this page?

1. The fastest way to lose weight: What you need to know
2. Diet strategies for faster weight loss
3. Using exercise to accelerate weight loss
4. How fast is safe? Healthy weight loss rates
5. How weight loss treatments can support fast and safe weight loss
6. Aim for sustainable weight loss
7. Frequently asked questions

The fastest way to lose weight: What you need to know

When you want to lose weight quickly, focusing on a calorie deficit is the most effective and safest approach. You can do this through diet, exercise or a combination of both.

What matters most is choosing an approach you can sustain – even when the goal is short-term.

Calorie deficit: the key to weight loss

A calorie deficit means you burn more calories than you consume. This is the fundamental mechanism behind weight loss.

A moderate deficit is safest – extreme calorie restriction can lead to fatigue, nutrient deficiencies and loss of muscle.

Why calorie deficit works

When your body is in a calorie deficit, it uses stored fat for energy, which leads to fat loss. Maintaining a calorie deficit consistently will help you lose weight safely without the need for extreme or unhealthy measures.

You can explore ZAVA's weight loss treatments for more information on effective ways to lose weight.

Diet strategies for faster weight loss

There are several diets that can lead to rapid weight loss, but it’s important to choose one that promotes sustainable and healthy habits. Examples of diet strategies that have worked for many people seeking fast weight loss are:

Intermittent fasting

Intermittent fasting involves alternating between eating periods and fasting periods, such as fasting for 16 hours and eating within an 8-hour window. Studies show intermittent fasting can be an effective way to reduce your calorie intake and encourage fat loss. You will need to avoid overeating during eating windows to maintain a calorie deficit.

Intermittent fasting is not suitable for everyone. For example, if you’re pregnant or have diabetes this approach should be avoided.

Low-carb diets

Low-carb diets reduce the intake of carbohydrates such as bread, pasta, rice, and sugary snacks. This can help you reduce overall calories and improve blood sugar control.

Be aware that early weight loss on low-carb diets is often due to water loss rather than fat.

High-protein diets

A high-protein diet can help you feel fuller for longer, preserve muscle while losing fat, and support your metabolism. Protein also has a slightly higher thermic effect than other foods, meaning that your body uses more energy and burns more calories to digest it. Learn more about the best high protein foods for weight loss.

Using exercise to accelerate weight loss

Exercise plays a crucial role in accelerating weight loss and promoting overall health. You can use different kinds of exercise depending on personal preference.

Cardio exercise

Cardiovascular exercises, such as running, swimming and cycling, are effective for burning calories quickly and improving cardiovascular health. These activities increase your heart rate and help you achieve a calorie deficit. Discover how much exercise is needed for weight loss.

Benefits of cardio

Cardio exercises can help burn fat and improve endurance. Consistent cardio can lead to fat loss while improving cardiovascular health, which is essential for long-term weight management.

Strength training

Cardio can help you burn more calories, but strength training is crucial for protecting muscle, especially during rapid weight loss. Lifting weights and performing resistance exercises helps build lean muscle, which boosts metabolism and burns more calories at rest.

Benefits of strength training

By increasing lean muscle mass, strength training raises your resting metabolic rate (RMR), which means you burn more calories even when you’re not exercising. Lifting weights ensures that your body burns fat while preserving muscle mass, preventing the negative effects of rapid weight loss, such as muscle loss and slower metabolism.

How fast is safe? Healthy weight loss rates

Most medical guidelines recommend losing 0.5 to 1kg per week. Losing weight faster than this increases the risk of muscle loss, nutrient deficiencies and a slower metabolism.

Losing weight too quickly can trigger metabolic adaptations that make weight loss harder to maintain and may negatively affect your health long‑term, which reinforces current recommendations for gradual weight loss.

4 reasons sustainable weight loss is important

Rapid weight loss might seem like a shortcut to quick results, but it often comes with significant downsides:

When you lose weight too quickly, your body may break down not just fat, but also muscle mass and other lean tissues, which can lead to a slower metabolism and make future weight loss harder.
Losing weight too rapidly can impair your resting metabolic rate (RMR), making it more challenging to sustain weight loss in the long term.
Research supports the idea that gradual weight loss – typically around 1 to 2lbs or 0.5 to 1kg per week – is more effective for long-term health and fat loss, as it helps preserve lean muscle and maintain metabolic health. One meta-analysis found that gradual weight loss results in better fat loss and helps preserve RMR, compared to rapid weight loss.
Rapid weight loss can cause nutrient deficiencies, as you might not be getting enough essential vitamins and minerals for your body to function properly. This can lead to fatigue, weakness, and other health issues, which could make maintaining weight loss long-term more difficult.

Gradual progress for long-term results

Aim for steady, consistent weight loss rather than quick fixes. This approach is more effective in the long run and will help you maintain a healthy weight without negatively impacting your health.

"The recommended rate of weight loss is typically 0.5 to 1kg or 1 to 2lbs per week. While faster weight loss may seem appealing, it can be harmful in the long run by leading to muscle loss and nutritional imbalances. For sustainable results, it's important to focus on gradual, healthy weight loss."

Dr Kathryn Basford Accreditations: MB, ChB, MPH

How weight loss treatments can support fast and safe weight loss

If you struggle to lose weight through diet and exercise alone, prescription weight loss treatments may offer additional support. These treatments are not quick fixes and work best when combined with healthy lifestyle changes. They may help you manage appetite more effectively so you can maintain a safe calorie deficit.

Wegovy (semaglutide)

Wegovy, a medication with the active ingredient semaglutide, helps reduce your appetite. Clinical trials have shown that Wegovy can lead to significant weight loss when used alongside a healthy diet and exercise plan.

Mounjaro (tirzepatide)

Mounjaro is another medication shown in studies to be highly effective for weight loss, sometimes outperforming semaglutide. A clinical trial found that adults with obesity (but without diabetes) treated with tirzepatide (Mounjaro’s active ingredient) lost more weight than those treated with semaglutide at 72 weeks. Participants on tirzepatide lost around 20.2% of their body weight compared with about 13.7% with semaglutide.

➤ Always use weight loss medications under medical supervision as part of a comprehensive treatment plan.

Aim for sustainable weight loss

While it’s tempting to aim for rapid weight loss, it is better to focus on gradual progress and long-term health.

Remember, sustainable weight loss is not just about shedding pounds quickly – it’s about maintaining healthy habits that support your overall wellbeing. Whether this is through diet, exercise, or medication, always prioritise health and safety in your weight loss journey.

Frequently asked questions

What are the fastest ways to lose weight through diet?

The fastest ways to lose weight through diet include intermittent fasting, low-carb, and high-protein diets.

Can intermittent fasting speed up weight loss?

Yes, intermittent fasting can help speed up weight loss by reducing calorie intake and boosting the body’s fat-burning processes.

What exercises burn the most calories?

Cardio exercises, such as running and cycling, burn calories quickly, while strength training helps preserve muscle mass.

Is it safe to use appetite suppressants for fast weight loss?

Appetite suppressants, such as Wegovy and Mounjaro, can be effective for weight loss, but should only be used under medical supervision.

How fast is it safe to lose weight?

Safe weight loss is typically around 0.5 to 1kg or 1 to 2lbs per week. This pace prevents muscle loss and ensures long-term sustainability.

Medically reviewed by

Dr Kathryn Basford

Dr Kathryn Basford is a GP based in London. She graduated from the University of Manchester and completed her GP training through Whipps Cross Hospital in London. Outside of work she enjoys baking and keeping active, running marathons, swimming, and triathlons.

Last reviewed: 26 Feb 2026