Is it healthy to lose weight fast? Here’s what the experts say.

Experts agree it’s not about losing weight fast. It’s about losing weight right. Read on to discover the risks, myths and science-backed alternatives to fast weight loss.
Published 27 October, 2022

Looking to lose weight fast but feeling overwhelmed by the amount of content online? We get it. The weight loss world is full of conflicting information – some nonsense and some downright dangerous – which can make it impossible to know where to begin.

Well, we’ve looked at the science to find the safest, most sustainable way to lose weight. Read on for more!

What does losing weight fast mean?

First things first, let’s look at what’s considered ‘fast’ weight loss. While everyone is different, anything more than 1-2lbs per week is generally considered to be losing weight too fast. While losing more can sound tempting, weight loss this fast is unsustainable and not recommended by medical experts.

Dr. Michelle May, award-winning health and wellness speaker, notes “People get so focused on weight loss they are willing to do unproven and potentially dangerous things that can backfire and cause serious health problems”.

That means you should stay away from:

• Starving yourself

• Very low-calorie or low-carb diets

• Weight loss supplements and pills

• Fad or crash diets and detox plans

• Extreme exercising

• Purging

Is it healthy to lose weight fast? In a word, no. Scientific research tells us that losing weight too quickly can have a negative impact on our health. The risks of losing weight too fast are:

It slows your metabolism

Losing weight fast and not eating enough can slow your metabolism, meaning your body burns fewer calories to conserve energy. And that’s the complete opposite of what you want…

You miss out on important nutrients

Cutting out a food group, starving yourself or taking weight loss supplements means you may not get enough of the nutrients and vitamins that your body needs. This can lead to digestive issues, loss of bone density, low immunity and even hair loss.

You lose muscle

If you’re eating a very low-calorie diet and the scales are dropping, it may be muscle mass that you’re losing, rather than fat. This actually makes it harder to lose weight, as muscle is key for burning calories.

It can increase the risk of gallstones

Research shows that gallstones occur in 12-25% of people that lost large amounts of weight over a short period. Ouch.

You are tired and irritable

You might have lost weight fast. But is that worth the serious fatigue, irritability and lack of productivity that come with too few calories? Probably not.

You’re likely to quit and gain weight

Losing weight in the fastest possible way – think crash diets and purging – can cause you to gain more weight in the future. That’s because extreme restriction can cause hormonal changes leaving you craving high-fat and sugar foods.

The healthy, sustainable alternative to losing weight fast

Now we know that extremely fast weight loss is not the way forward, it’s time to look what does work.

Research shows that sustainable weight loss of no more than 2lbs a week is the best option for healthy, long-term success. Enter WeightWatchers.

Using a science-backed, restriction-free points system, we were named the #1 doctor-recommended weight-loss programme according to a survey of 14,000 doctors†. Here’s what we’re all about…

Always backed by science

From day one, the WeightWatchers approach has been rooted in science. We use the latest clinical and behavioural research to help members build life-changing habits and reach their weight-loss goals.

We’ve been working in partnership with the NHS since 2005, helping thousands of people to lose weight after a referral.

Our 12-strong Science Team (made up of psychologists, dietitians, and behavioural scientists) continue to make sure we evolve with the latest findings to offer the most scientifically sound plan available.

To find out more about our proven approach, click here.

Points mean healthier choices

Research has proven that individualised approaches to weight loss lead to better success than a one-size-fits-all approach.

That’s why, with WeightWatchers Programme, members receive a personalised ‘point’ budget designed specifically for them by our nutrition experts. A super-smart food algorithm converts calories and complex nutrient data into one number – a food’s Points value – to make tracking (and weight loss) effortless.

Long-term results, no FOMO

Life’s too short to cut out your favourite dishes, desserts and drinks. In fact, banning certain foods only makes you crave them more. That’s why, with WeightWatchers, absolutely no food is off the table – as long as it’s eaten in moderation. And because it’s no fun to live under lock and key either, your programme is designed to fit around your life. You can still go to those work drinks, or that birthday party, or have a takeaway once in a while – which makes it so much easier to stick to!

A strong support system

The fastest ways to lose weight often mean going it alone. Meanwhile, WeightWatchers members have access to a huge support system of members and coaches, either online or in person. There’s also our handy WeightWatchers app – the pocket-sized companion for logging food, getting recipes, chatting to coaches, accessing workouts and tracking progress.

Your weight loss questions, answered

Is losing weight fast healthy?

Extremely fast weight loss is not healthy. It can cause a slower metabolism, loss of muscle, increased risk of gallstones, and deficiency in nutrients that your body needs. This can lead to a variety of health issues, including weaker bones, digestive problems and low immunity.

How fast should I be losing weight?

Doctors recommend losing no more than 2lbs per week to keep it healthy and sustainable.

Can losing weight too fast cause heart problems?

Very fast weight loss through crash diets can lead to a lack of essential nutrients, which can in turn cause heart-related conditions, including an irregular heartbeat. Extreme exercising when you’re not accustomed to it can also be dangerous for your heart.

Is it better to lose weight fast or slow?

When it comes to weight loss, slow and steady wins the race. Fast weight loss can lead to health issues and there’s more likelihood of putting the weight straight back on. Slower = more sustainable and healthier.

What is the fastest way to lose weight?

The fastest ways to lose weight are also the most dangerous and least sustainable. With our simple, personalised plan that’s backed by science, you can lose weight and keep it off, while still enjoying the things you love.