The Basics

Written by the doctors and editors at UpToDate

Am I at a healthy weight?

It depends on your height and your overall health.

Doctors use a measure called "body mass index," or "BMI," to help understand a person's weight. They use your weight and height to calculate your BMI (figure 1). Based on this number, you fall into 1 of these categories:

● Underweight – BMI under 18.5

● Healthy weight – BMI between 18.5 and 24.9

● Overweight – BMI between 25 and 29.9

● Having obesity – BMI 30 or greater

Your doctor or nurse will often calculate your BMI at your medical appointments. But it's important to remember your weight and BMI are just 1 piece of your overall health. Someone with a lower BMI might not be healthy overall, and someone with a higher BMI can still be healthy.

How does my weight affect my health?

Having obesity increases the risks of many different health problems. It can also make it harder for you to move, breathe, and do other things people who are at a healthy weight can do easily.

People with obesity are more likely to get diabetes, heart disease, cancer, and lots of other health problems. They also tend to have shorter lifespans than people with a healthy weight. That's why it's important to try to keep your weight in a healthy range.

How can I lose weight?

You can start by talking to your doctor or nurse. They can help you make a plan to lose weight in a healthy way. They can also help you understand how many calories your body needs for energy. Losing weight takes work and can be hard, so it helps to have support.

The best weight loss plans help you have a healthy view of eating and exercise. With a good weight loss plan, many people can lose weight and keep it off. Reducing calories in your diet, burning calories through exercise, or both can help you lose weight:

● Diet – There is no specific diet plan that works for everyone. Many "trendy" weight loss programs can end up being more harmful than helpful. Any diet that reduces how many calories you eat can help you lose weight, as long as you stick with it. You should try to find an eating pattern that works for you.

It can also help to work with a dietitian (food expert). They can help you make healthy diet changes while making sure you get the nutrients your body needs.

● Movement and exercise – Even gentle forms of exercise are good for your health. You can walk, dance, garden, or even just move your arms while sitting. For weight loss, the important thing is to increase how many calories you burn by moving more.

Combining a healthy diet with regular physical activity can help you get the best results. This is important even if your doctor recommends treatment for weight loss.

If you change your eating or exercise habits for a short time, you might lose weight. But you will regain the weight if you go back to your old habits. Weight loss is about changing your habits for the long term.

Can medicines help with weight loss?

Sometimes. Prescription weight loss medicines work by reducing your appetite or by changing how you digest food.

Your doctor might recommend medicine if you have not been able to lose weight in other ways, and you:

● Have a BMI of 30 or greater, or

● Have a BMI between 27 and 29.9 and also have weight-related medical problems, such as diabetes, heart disease, or high blood pressure

When doctors prescribe medicines for weight loss, they sometimes choose "GLP-1" medicines. This type of medicine was originally used for treating diabetes. But they can also help with weight loss in some people without diabetes. Examples include:

● Tirzepatide (sample brand names: Zepbound, Mounjaro)

● Semaglutide (sample brand names: Wegovy, Ozempic)

● Liraglutide (sample brand name: Saxenda)

● Orforglipron (brand name: Foundayo)

Most of these medicines come as shots that go under the skin. Some come as pills you take by mouth. They work by increasing the amount of insulin your body releases after eating. (Insulin is a hormone that helps control blood sugar.) They also slow digestion and make you feel full more quickly.

These medicines can work well for weight loss. But they can also cause side effects, like nausea, vomiting, diarrhea, and constipation. And they can be expensive. Most people have to keep taking these medicines long term. If you stop the medicine, you will likely gain back the weight you lost.

There are other medicines that can be used for weight loss, too.

Medicines can be a helpful part of treatment for some people. But even if your doctor does prescribe medicine, they will also still recommend making lifestyle changes. This can help improve your overall health.

If you are interested in taking medicine to help you lose weight, talk with your doctor. They can help you understand your options.

Can I try herbal or non-prescription medicines to lose weight?

Be careful about non-prescription ("over-the-counter") products advertised to help with weight loss:

● Many herbal weight loss medicines do not work, and some are unsafe. Check with your doctor or pharmacist before you take any herbal weight loss medicines.

● There is also an over-the-counter version of a prescription medicine called orlistat (brand name: Alli). It is probably safe to try, but it can cause unwanted side effects, such as cramps, burping, and gas.

● Some weight loss medicines are sold over the internet. But they can contain harmful ingredients and be unsafe.

How does weight loss surgery work?

It works by making your stomach smaller. Some types of surgery also change the path food takes through your digestive system. With these types, your body absorbs fewer calories and nutrients from food.

Weight loss surgery is not an option for everyone. If you are thinking about surgery, your doctor can talk to you about your situation and options. They can also talk to you about the risks and benefits of surgery.

How do I decide if weight loss treatment is right for me?

If your doctor suggests weight loss treatment, ask these questions:

● How much weight can I expect to lose, and how long will it take? – This depends on the treatment. Some weight loss medicines start working quickly, often within a few months. For surgery, the amount of weight loss and how long it takes depends on the specific procedure.

● What are the risks of this treatment? – All weight loss medicines can cause side effects. All weight loss surgeries can lead to infection, bleeding, needing other procedures, and even death. To reduce the risk of these problems after surgery, make sure your surgeon is very experienced and you are treated at a certified "Center of Excellence."

● Which diet and lifestyle changes will I need to make? – Weight loss treatments are not "shortcuts" you can take to avoid making lifestyle changes. People must also change how they eat and how active they are. No single weight loss treatment works on its own. Sometimes, people can get surgery only after they lose some weight on their own through diet and exercise first. Working with a dietitian can help.

● Will I be able to process food normally? – Some types of weight loss surgery leave people unable to get all the nutrients they need from food. They must take vitamin and mineral supplements for the rest of their lives.

All topics are updated as new evidence becomes available and our peer review process is complete.

This topic retrieved from UpToDate on: Apr 15, 2026.

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figure 1: Your body mass index (BMI)

Find your height (in feet and inches) in the top row. Then, find your weight (in pounds) in the first column. Now, find where the column for your height and the row for your weight meet. That is your BMI. For example, if you are 5-feet-9-inches tall and you weigh 260 pounds, your BMI is 38.

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