How Long Does It Take To Lose Weight?

Nearly three-quarters¹ of Americans are overweight, and for many, losing weight is a common goal. But many people begin their weight loss journey without understanding why and how weight loss happens or how long the process might take.

Before trying to lose weight, it's important to seek the right knowledge and advice. The weight loss process is much quicker and easier when you’re well-informed.

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How weight loss happens

Weight loss revolves around one simple idea: a fine balance between calories consumed versus energy used. A calorie is a measure of how much energy you get from food and drinks. In order to lose weight, you must burn more calories than you consume, which is achievable either by consuming fewer calories or burning more energy, for example, by exercising. While this seems simple enough, it's important to look at the facts behind this concept.

Your metabolism influences your body’s basic energy needs, but what and how much you eat and drink plus the amount of physical activity you do also influences your weight.

What is metabolism?

Metabolism is a complex chemical process where food and drink are broken down by your body and converted into the energy you need to stay alive and function properly.

Each person has a unique metabolism. Your metabolic rate determines how quickly your body processes and burns the food and drink you consume. People with a slower metabolism might find it harder to lose weight while those with a faster metabolism might find it easier.

Your individual metabolism is the most important factor in how many calories your body needs to function throughout the day. It is affected by many different factors, such as age, gender, genetics, hormones, general health, lifestyle habits, exercise, and diet.

What factors influence how fast you can lose weight?

The first step towards losing weight is to ensure the amount of calories you burn is greater than the calories you consume. However, many other factors influence your metabolism and how fast you can lose weight.

Your current weight

Your current weight determines how fast your body burns calories; the more you weigh, the faster your body burns energy. For example, someone who weighs 300 pounds burns more calories each day on average than someone who weighs 150 pounds, even while at rest. This means you'll lose weight more quickly at the start of your diet because you'll be heavier.

Muscle mass

The more muscle mass you have, the faster you will burn calories. If you are 150 pounds and muscular, you will burn calories at a quicker rate than someone who weighs the same but has less muscle mass.

Sleep habits

Poor sleep can make it challenging to lose weight. This is because, without enough high-quality sleep, your metabolism starts to slow down. Bad sleeping habits also raise your cortisol levels. Cortisol is a stress hormone, so when you have high cortisol levels, you tend to crave sweet, fatty, or salty foods which are detrimental to weight loss.


As you age, your metabolism will naturally slow down and you will start to lose muscle mass. This makes it more difficult for an older person to lose weight. This doesn't mean it's impossible though! Maintaining activity levels throughout your life can help you preserve muscle and lose weight.


They may be impossible to change, but it's thought that dozens of genes² affect your metabolism and how you lose and gain weight.

Weight loss history

If you've tried losing weight in the past but put it back on, you might find it harder to shed weight this time around. This is due to changes in your hormones and metabolism. For example, losing weight causes your metabolic rate to slow, making it harder to shift it again.


If you already live a healthy lifestyle in terms of diet, rest, and exercise, it might be harder for you to lose weight. It can be frustrating to think you’re doing everything “right” but you’re not getting the results you want. If this sounds familiar, it may be time to take a closer look at your diet and the types of exercises you're doing. Perhaps it’s time to switch up your routine.

On the other hand, if you’re starting your weight loss journey with an unhealthy lifestyle, getting more active and switching to a nutritious, well-balanced diet will result in faster weight loss.

Keep in mind that you are unique and your body is different from everyone else’s. What works for one person might not work for you. For example, doctors and scientists are just beginning to understand the role genetics play on a person’s weight, and there's still much that remains unknown.

How to lose weight as quickly as possible

If your goal is to lose weight as quickly as possible, try following these simple strategies to help you lose weight fast without damaging your health.

Get professional advice

If you want to lose weight, the best thing you can do is talk to your doctor. They will be able to rule out health conditions that are preventing you from losing weight. What’s more, rapid weight loss can put stress on your body, so it's important to lose weight under the supervision of your doctor.

Your doctor can provide you with some suggestions to help you with weight loss, and they may even refer you to a nutritionist. If your doctor concludes that your weight is damaging your health and wellbeing, they might suggest another method of weight loss, like medication or surgery.

Do more exercise

Exercise plays an important role in weight loss, and some exercises are more effective than others. For example, strength training (lifting weights, doing pushups, etc.) helps you to build and tone muscle, while aerobic exercise burns calories most effectively and quickly. Aerobic exercise includes cycling, running, walking, swimming, and any other exercise that really gets your heart pumping.

Aim to do 150 minutes or more of cardio each week. Strength training can be important too, so you shouldn't neglect it. When you have more muscle mass, your body naturally burns calories faster. Try to do a little strength training each week to help build lean muscle.

Consume a balanced diet rich in protein

A diet rich in protein can help you build muscle. Some extreme diets recommend consuming mostly protein, but remember that following a crash or fad diet is never a good idea.

Your genetics are an important factor in determining which diet works best for you, so you may want to talk to a qualified nutritionist. Just because someone you know lost 100 pounds following a particular diet doesn't mean it will work for you because your body and genetics are different.

When and why fast weight loss isn’t healthy

When people want to lose weight, they generally want to do so as quickly and easily as possible. But losing weight quickly is not always the healthiest option as it can negatively impact your health.

Slow, gradual weight loss achieved by making sustainable changes to diet and lifestyle is usually the best way to achieve your goals unless your doctor recommends another method.

On average, aim to lose between half a pound and two pounds each week. Any more than this might put too much strain on your body. If you lose weight too quickly, your body may lose muscle instead of just losing fat. As a rule, never reduce your daily calorie consumption to below 1,200 calories for women and 1,500 calories for men, unless you're under the supervision of a doctor or dietitian.

When you don’t consume enough calories or cut certain food groups (like dairy or carbs) out completely in order to lose weight, you might miss out on important nutrients, and this can negatively impact your health. Short-term effects may be fatigue and increased susceptibility to illness, and in the long run, it can lead to decreased bone density and strength.

The lowdown

To achieve your weight loss goals in a healthy way, without putting excess strain on your body, aim to make gradual and sustainable changes to improve your lifestyle. This might mean switching to a more nutritious, well-balanced diet, or increasing your activity levels. You need to find a balance that works for you; no two bodies are the same. Remember to speak to a doctor or nutritionist to get expert advice tailored to your body, lifestyle, and genetics.

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We make it easy for you to participate in a clinical trial for Weight management, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

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