Does rapid weight loss result in quicker weight gain down the line?

When deciding to shed some pounds, people usually look for immediate results. This may be motivated by an upcoming event or the need to ease physical discomfort and health concerns.

Most expert guidelines suggest that slow weight loss is the best approach for treating obesity. This is because fast weight loss is often regained quickly, while slow weight loss is seen as more sustainable and healthier. 

Many programs that claim to offer the quickest way to lose weight are fad diets that restrict calories or eliminate certain foods. However, there is debate about whether slow and steady weight loss is more effective and safer than fast weight loss.

How to know the difference between slow and fast weight loss?

Experts usually advise aiming for a weight loss of 0.5 to 1 kilogram per week, a gradual process [1]. Rapid weight loss, also known as fast weight loss, is when one loses more than 1 kilogram weekly for several weeks.

How to know the difference between slow and fast weight loss?

What does the research say about rapid weight loss?

Numerous well-executed studies have explored various weight loss methods. One study involved 200 participants randomly assigned to either a fast or slow weight loss approach to reduce their weight by 15% over 12 or 36 weeks, respectively [2].

The fast weight loss group participants were instructed to follow a very low-energy diet, which included meal replacements such as shakes, bars, and soups. They were required to replace all three meals with these options each day. 

On the other hand, the slow weight loss group was advised to consume 500 fewer calories than their daily energy expenditure, as recommended by the Australian Guide to Healthy Eating. They were allowed to consume one to two meal replacements per day.

During this time, the fast weight loss group had a higher success rate of achieving 12.5% or more weight loss than the slow weight loss group, with 81% and 50%, respectively.

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Following the first phase, individuals who had lost 12.5% or more of their weight were subsequently put on a diet intended for weight maintenance, which lasted for around 2.75 years. 

At the three-year milestone, the slow and fast weight loss groups had a 76% rate of individuals who had regained their lost weight.

Regardless of the speed at which the weight was lost, it was regained. Yet, a study involving 101 postmenopausal women revealed that those who lost weight quickly had better outcomes than those who lost slowly at the three-year mark [3].

Is slow weight loss better than fast weight loss?

When it comes to losing weight, there are other important factors besides just shedding pounds. Changes in body composition and bone mineral density should also be considered. 

A large meta-analysis, which combines the results of previous well-conducted studies on the topic, illustrates this point. 

According to this analysis, the slow and fast weight loss resulted in similar weight loss. However, slow weight loss led to better outcomes in terms of metabolism or how many calories we burn at rest.

Moreover, there was no variation in the loss of fat-free mass or muscle mass between the groups that lost weight slowly and those that lost weight quickly. 

However, the group that lost weight slowly had more significant reductions in fat mass, resulting in a better fat-to-muscle ratio. 

Additionally, slow weight loss is better for bone density, as rapid weight loss can lead to twice as much bone loss and increase the risk of brittle bones or osteoporosis.

What other diet approaches should we consider?

Studies have found that the specific macronutrient diet you choose – high or moderate protein, low or high carbohydrate, or low or high fat – does not significantly affect weight loss outcomes. 

Similarly, trendy methods of reducing calorie intake, like intermittent fasting or time-restricted eating, do not produce better weight loss results than previous methods [4]. 

The reason for this is that our bodies have a natural tendency to resist weight loss.

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Factors to consider when you want to lose weight


If you lose weight, your resting metabolic rate (the energy you burn at rest) will decrease. Keeping your resting metabolic rate high is essential to maintain your weight loss. 

However, even if you regain weight, your resting metabolic rate will not recover to its pre-dieting level.

Studies have shown that losing weight gradually helps maintain your resting metabolic rate more than losing weight quickly. 

Additionally, a weight loss program that combines exercise with a healthy diet is more effective than simply focusing on diet alone.

Side effects 

Although restrictive diets may provide quick results, research shows they can have negative consequences. 

These include an increased chance of gallstones and deficiencies that can lead to weakened immune function, tiredness, and decreased bone density. 

Following such diets can also make it challenging to fulfill your nutritional requirements.

Side effects 
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It’s important to be cautious of fast weight-loss diets that limit or eliminate foods necessary for long-term health. 

Often, these diets prohibit carbohydrates, but it’s essential to know that wholegrain carbohydrates are a crucial source of nutrition that aids in weight loss and disease prevention. 

Additionally, relying on meal replacements as a strict diet plan is not a sustainable solution for the long haul.


Maintaining weight loss can be challenging, as our bodies naturally strive to maintain a certain weight through adjustments to our biological systems and physiological changes that encourage weight regain. 

Regardless of how the weight is lost, this can be a difficult hurdle to overcome. This survival response originated from our hunter-gatherer ancestors, who developed it to adapt to periods of food scarcity.

Achieving long-term weight loss success boils down to the following:

  1. Using evidence-based programs that are informed by the science of obesity.
  2. Working with qualified healthcare professionals for safe weight loss.
  3. Changing your lifestyle gradually can include improving your diet, exercising regularly, and ensuring adequate sleep.

All these can help you form healthy habits that will last a lifetime.

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The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.