What Is Weight Loss

Obesity is a multi-faceted and complex medical condition, characterized by a person being grossly fat or overweight. One can be overweight without being obese—some people weigh more than the average for their height because of muscles, bone, or water weight. But if you have too much fat, it can endanger your health and put you at serious risk of health conditions such as heart disease, diabetes, and high blood pressure.

According to the National Health and Nutrition Examination Survey, more than 2 out of every 3 adults—and 1 out of every 3 children—are overweight, and more than half of these overweight people are obese.

The main tool used to measure body fat—and can hence tell whether one is overweight or obese—is the body mass index (BMI). You can calculate your body mass index by dividing your weight in kilograms (1 kg ≈ 2.2 lb) by your height in meters squared (1 m ≈ 3.28 ft; 1 m2 ≈ 10.76 ft2). You can find out your BMI online by entering your height and weight into the BMI calculator provided by the Centers for Disease Control and Prevention.

A typical healthy person has a BMI of 18.5 to 24.9. A BMI of 25 or greater is considered overweight, and a BMI of 30 or greater is likely to be obese.

BMI Weight status
Below 18.5 Underweight
18.5-24.9 Normal
25.0-29.9 Overweight
30.0-34.9 Obese (Class I)
35.0-39.9 Obese (Class II)
40.0 and higher Extreme obesity (Class III)

BMI is not a perfect measurement. Some people may have a BMI in the overweight or obese category, even if they don’t have a lot of body fat. Very muscular people are one example, and some people may have a high weight because of bone mass, excess water, or a stocky build. But for most people, BMI is a reasonable place to start when you want to know if you have a healthy weight.

Fortunately, if you are overweight or obese, even a little weight loss can help you improve your health and prevent some of the health problems that obesity may cause. Losing weight isn’t easy. It can take time and effort to get rid of excess pounds and keep them off. But losing weight can make a permanent difference in your overall health

What Causes Weight Loss

Ultimately, body weight is the result of genetics, metabolism, environment, behavior, and culture. But the most common causes of obesity and weight problems are overeating and physical inactivity. The essential equation remains: if you eat more calories than you use in a day, then you will gain weight, as your body stores those extra calories as fat. If the number of calories you eat in a day is about the same as the number of calories you use, your weight should stay more or less the same. And if you use more calories than you take in, then you will likely lose weight.

Put a different way, obesity is caused by taking in more energy (calories) than your body uses. All living things need energy. Your body gets this energy from the foods you eat. Your body uses energy all the time, but it uses more energy when you’re moving than it does when you’re sitting still.

So if your weight has been constant for a long time and then starts increasing, it may mean that you’re eating more calories, or that you’re exercising less, or it could be caused by something else that changes the way your body uses energy, such as:

  • Being pregnant
  • Getting less sleep
  • Some medications or health conditions

Risk Factors For Weight Loss

Not everyone has the same risk of obesity. Some factors that can make you likely to be overweight or obese include:

  • Genetics. Different bodies use energy differently, and your genes may affect how efficiently your body uses energy. A person is more likely to become obese if one or both parents are obese. Genetics also affect fat regulation hormones, which can impact weight. One genetic cause of obesity is leptin deficiency. Leptin—a hormone produced in fat cells, as well as in the placenta—controls weight by signaling the brain to eat less when body stores of fat are too high. If the body does not produce sufficient leptin, however, or leptin cannot signal the brain to eat less, then this measure of hormonal check and balance is lost, and can lead to obesity. esearch is currently being done on the role of leptin replacement as a treatment for obesity.
  • Learned habits. Genes aren’t all you inherit from your parents. The eating and exercise habits you learn as a child may stick with you into your adult life.
  • Inactivity. Days behind a desk or evenings in front of a TV can make it hard to use the calories you eat. Sedentary people burn fewer calories than people who are active—and this physical inactivity is strongly correlated with weight gain.
  • Overeating and unhealthy eating habits, such as skipping breakfast, eating too much fast food, or not eating enough fruits and vegetables can lead to weight gain.
  • Eating a diet high in fat, sugar, and carbodydrates contributes to weight gain, especially when a person over consumes food. Research has shown that simple carbohydrates (like sugars, white bread and pasta, desserts, soft drinks, beer, wine, and more) contribute to weight gain because they are more rapidly absorbed into the bloodstream than complex carbohydrates (like whole wheat bread and pasta, brown rice, grains, vegetables, raw fruits, and more)—causing a more pronounced insulin release after meals than complex carbohydrates. Research has shown that this higher insulin release contributes to weight gain.
  • Quitting smoking. In the long run, quitting smoking can be a great benefit to your health, but in the short term it sometimes leads to stress-related eating and weight gain.
  • Pregnancy. The weight a woman gains while pregnant is usually more than the weight of the baby, and it can sometimes be hard to lose the extra weight after giving birth.
  • Lack of sleep can cause changes in hormones that affect appetite, decrease your willpower, and make you too tired to get up and move. You may also crave foods high in calories and carbohydrates, which can contribute to weight gain.
  • Taking certain medications, such as antidepressants, lithium, corticosteroids, anticonvulsants, diabetes medications, oral contraceptives, or certain medications for heart problems. Weight gain may also be seen with some high blood pressure medications and antihistamines. The reason for the weight gain with the medications differs for each medication. It’s important to discuss your medications with your healthcare professional if you are experiencing unwanted weight gain. Don’t discontinue taking your medication, as that could have a potentially serious impact on your health.
  • Your age. As we age, hormonal changes and a less active lifestyle increase risk of obesity. As well, muscle mass in the body tends to decrease with age, which leads to a decrease in metabolism. As hormonal shifts and muscle mass changes occur, calorie needs are reduced, which can make it harder to keep off excess weight. If you are not more careful with what you eat, and don’t become more physically active as you age, you’ll likely gain weight.
  • Social and economic issues can have a big impact on weight problems and obesity. It can be time-consuming and hard to cook healthy food on a budget, and if you work extra hours to make ends meet, you may end up relying on unhealthy fast foods that seem “cheap.”  Perhaps you were not taught how to cook healthy food. As well, the people you spend time with may influence your weight—you’re more likely to become overweight if you have overweight relatives or friends.
  • Psychological factors. For some people, emotions influence eating habits. Many people eat excessively in response to emotions such as boredom, sadness, stress, or anger. While most overweight people have no more psychological disturbances than normal weight people, about 30% of the people who seek treatment for serious weight problems have difficulties with binge eating.
  • A medical problem, such as Prader-Willi syndrome, Cushing’s syndrome, hypothyroidism, insulin resistance, polycystic ovary syndrome, among other conditionsare also contributors to obesity.

Diagnosing Weight Loss

When you visit your doctor about a weight problem, your doctor will check your height and weight, and calculate your BMI. Your doctor will also ask you questions about your eating and exercise habits, what you think might be causing or contributing to your excess weight, and how much weight you hope to lose. Other questions may focus on:

  • Your medical history
  • How your weight affects your day-to-day life
  • What methods you’ve tried, if any, to lose weight in the past, and whether they have been successful or not
  • How ready you are to make the necessary changes in your life
  • What obstacles may get in your way

Your doctor will also perform a physical exam to check vital signs such as your heart rate and blood pressure. Measuring the circumference around your waist can tell your doctor some information about how much your weight is likely to affect your overall health. Fat stored around your waist, sometimes referred to as abdominal fat, may further increase your risk of diseases such as diabetes and heart disease. Women with a waist measurement (circumference) of more than 35 inches and men with a waist measurement of more than 40 inches may have more health risks than those with smaller waist measurements.

In all likelihood, your doctor will also order blood tests to check for health problems associated with overweight and obesity. Some of the lab tests your doctor may request include:

  • Fasting glucose level
  • Cholesterol test
  • Liver function
  • Thyroid test

Your doctor may also want to check your heart function with an electrocardiogram or other tests.

The information from this exam and tests will help your doctor get a sense of your weight and your overall health, to understand how much weight you need to lose and what the best approach will be to get you to that goal.

Symptoms of Weight Loss

If you find yourself gaining weight, you may want to talk to your doctor about whether your weight is in the healthy range, and whether you need to change your eating and exercise habits to keep yourself in shape. Some indicators that you may be gaining weight include:

  • Clothes that have gotten tighter or don’t look the same
  • A change in how you look in the mirror or how much you weigh when you step on a scale

Indicators that you may be overweight or obese include:

  • A BMI above 25, especially if it’s 30 or higher
  • A waist circumference of 35 inches (88 cm) or more if you’re a woman, or 40 inches (102 cm) or more if you’re a man


Being overweight can lead to a number of serious health problems, including:

  • Type 2 diabetes
  • High blood pressure
  • Heart disease or stroke
  • Breathing disorders
  • Cancer
  • Depression
  • Osteoarthritis
  • Sexual health issues, such as erectile dysfunction

Being moderately obese (BMI 30-35) can shorten your lifespan by 3 years. Morbid obesity (BMI 40-50) can shorten your life by 10 years. At the high end, extreme obesity (BMI > 55) may shorten lifespan by as much as 14 years.

The good news is that losing just 15 to 20 pounds and keeping it off can reduce your risk of diabetes, heart failure, and other serious complications by 10% to 25%.

Living With Weight Loss

Losing weight isn’t easy. It can take a lot of willpower to stay on track, and no one else can do it for you. So what are some things you can do to help you keep yourself moving forward? Here are a few tips:

  • Get support. No one else can lose your weight for you, but having a friend to talk to can help a great deal. This can be a friend, or a support group, or anyone who can listen to you without judging.
  • Be realistic about your goals. Talk with your doctor about the best goal for you, but in general a good plan is to aim to lose 1 to 2 pounds per week. This kind of weight loss requires you to use 500 to 1,000 calories more than you eat each day.
  • Progress and process goals. You can also divide your goals into progress goals (e.g., lose 1 pound each week) and process goals (e.g., exercise at least 4 days a week). Process goals may not be as obvious as progress goals, but they are still important because they help you change your habits.
  • Don’t starve yourself. Eat breakfast every day. Skipping a meal often does more harm than good. And eat more fruits and vegetables, so that you can reduce calories without sacrificing flavor or fullness.
  • Move your body when you can. You might not be able to get to the gym every day, but you can find little things you can do to keep moving, like a short walk on your lunch break, or parking further from the store and walking, rather than circling looking for a close parking space.
  • Acknowledge that there will be setbacks. But a slip doesn’t have to be a collapse. If you fall behind on your goals, accept that you slipped up, and start fresh.


The U.S. Preventive Services Task Force recommends that doctors screen all adults and children aged 6 and over for obesity, and offer counseling and weight loss assistance for any patients with a BMI of 30 or higher. If you don’t know whether you have a weight problem, you can ask your doctor to check your BMI and screen you for weight-related health issues.

You can screen yourself for overweight and obesity using an online BMI calculator provided by the U.S. Centers for Disease Control and Prevention.


If you are not currently overweight, healthy eating and exercise habits can help keep you at a healthy weight and prevent overweight, obesity, and related health problems. And the sooner you start, the better. If you have children, then setting a good example and encouraging your children to maintain a healthy lifestyle can help prevent weight issues in the future. Some things you can do to help maintain a healthy weight for yourself and your children include:

  • Choose healthy foods, such as fruits, vegetables, and whole grains.
  • Serve reasonable portion sizes, and watch out for large portions when eating out.
  • Find active, outdoor activities that you enjoy. If you have a family, focus on finding things that everyone can enjoy together.
  • Limit time on computers, TVs, video games, and other screen time. 2 hours of screen time or less per day is best. Focus on finding active things to do instead.

Keep track of your weight, your waist measurement, and your BMI, and track your kids’ growth as well.

Common Treatment

The first step in weight loss treatment is usually lifestyle changes. Changing the way you eat and getting up to move more often will help you lose weight and get yourself in shape. The general idea is to make sure that the number of calories you use in a day is just a little bit more than the number of calories you consume, so that your body will start to feed off your excess body fat to replace the calories it isn’t getting through food.

There is no one right way to change your eating habits; different approaches work for different people. Some approaches that may help include:

  • Counting calories. This may be the most straightforward approach–measuring the calories you eat in a day and keeping as close as possible to a number just under the calories you use. Normally that’s about 1,200 to 1,500 calories for women or 1,500 to 1,800 calories for men.
  • Choosing filling foods with fewer calories. Serving larger portions of low-calorie foods can help you feel full without growing your waistline.
  • A healthy-eating plan such as the Mediterranean diet, based on fruits, vegetables, whole grains, and lean proteins such as beans and fish.
  • Limiting specific food types, such as fats, carbohydrates or sugars.

Watch out for fad diets that offer a quick fix. If you want to keep the weight off for the long term, then you need to find a long-term plan that works for you.

Developing an exercise regimen is also a very helpful step in losing weight. Aim to get at least 150 minutes of moderate exercise per week–or half an hour of exercise, five days a week. If you can’t find a half hour at one time, it’s OK to break it into smaller blocks throughout the day. It also helps to find ways to increase the amount you move throughout the day, such as taking the stairs instead of the elevator, or walking to places you would normally drive.

If it’s hard for you to stick with your weight loss program, you may benefit from behavior modification techniques to help you change. These may include:

  • Counseling with a therapist to help you work through issues and keep yourself on track
  • A support group where you can talk with other people going through the same challenges

If you are still struggling to lose weight without success despite diet, exercise, and other strategies, then there are medicines to help you lose weight. Your doctor may prescribe medical treatments for weight loss if your BMI is 30 or higher, or if you have weight-related complications and a BMI above 27.

Keep in mind, though, that medical weight loss treatments are intended for use alongside lifestyle changes, not to take their place. If you don’t stay active and keep watching what you eat, then weight loss medicines aren’t likely to help as much. And when you stop taking a weight loss medicine, you may regain much of the weight you lost. Prescription medicines for weight loss include:

  • Orlistat (Xenical), which stops your stomach from absorbing fat. Lower-dose orlistat is also sold over the counter as Alli.
  • Lorcaserin (Belviq), which alters chemicals in your brain to decrease your appetite and help you feel full. However, if you don’t lose about 5% of your body weight in the first 12 weeks of treatment, then lorcaserin probably won’t work for you. Pregnant women should not take lorcaserin.
  • Phentermine (Adipex-P, Suprenza) for short-term use–though you will need to find another way to keep the weight off in the long term.
  • Phentermine-topiramate (Qsymia), which combines phentermine with an antiseizure medication to make it safe for long-term use. If you don’t lose 5% of your body weight in the first 12 weeks, your doctor may need to stop this treatment or up your dose. This treatment is not appropriate for pregnant women.

If other treatments don’t help you, weight loss surgery may help you lose up to a third of your excess body weight, but you will still need to watch what you eat if you want to keep the weight off. Surgery may be an option, if:

  • Your BMI is 40 or higher
  • You have a serious weight-related problem and a BMI of 35 or higher
  • You’re committed to making the lifestyle changes you need to make surgery work.

There are several types of weight loss surgeries. Some of the most common surgical treatments for weight loss include:

  • Gastric bypass, in which the surgeon creates a small pouch at the top of your stomach and connects it directly to your small intestine, so that the food you eat skips your stomach and goes straight into the intestines. Gastric bypass is very effective for long-term weight loss and may help with type 2 diabetes and other complications, but it may cause blood clots, or you may require repeat surgery.
  • Laparoscopic adjustable gastric banding (LAGB, or Lap Band), in which the surgeon puts an inflatable band around your stomach and uses this band to cinch your stomach into 2 sections, connected by a narrow passage. Health risks include infections, blood clots, or the need to reoperate.
  • Gastric sleeve, a newer, experimental treatment in which a part of your stomach is removed, to give you a smaller stomach. The risks and benefits of this treatment are still being studied.
  • Biliopancreatic diversion, a somewhat riskier treatment in which most of the stomach is surgically removed. This highly effective surgery is usually reserved for people with a BMI of 50 or more, because of the risk of malnutrition and surgical complications.

Complementary and Alternative Treatment

Alternative and complementary treatments, by definition, aren’t as well studied as conventional medicine—and they generally aren’t as well regulated either, so you should be cautious about using alternative treatment, and always tell your doctor about any alternative treatments you use, as they may have dangerous side effects, or they might interact with your other treatments. Herbal treatments that have been tried for weight loss include:

  • Acai berry
  • Bitter orange
  • Green tea

At present there isn’t enough evidence to say for sure whether acai and bitter orange are safe or effective. Green tea appears to be safe, but studies have shown only minor, non-significant improvement in weight loss, if any at all.

Ephedra for weight loss has been banned in the United States, because it causes risk of heart disease or stroke, which can far outweigh the short-term weight loss benefits.

Research suggests that mind-body techniques such as yoga and meditation may be helpful as part of a larger program. Other techniques, including hypnosis and acupuncture, do not seem effective according to the most current studies, although large, well-controlled studies have not yet been performed.

Care Guide

Keeping weight off after you’ve lost it can be as hard as or harder than losing the weight in the first place. Many people do suffer relapses and regain some or all of the weight they lost. However, others do manage to keep it off. Some people, including many doctors, will say that 95% percent of people who lose weight will gain it all back–but that figure is based in a small study that’s over 50 years old. More recent estimates suggest that the 95% figure is accurate for crash diets and weight loss fads, but not for all people who make a concerted effort to lose weight. Overall, more than a third of people who lose weight can keep it off for at least 3 years.

Things you can do to help you lose weight and keep off the weight you’ve lost include:

  • Learn about obesity and weight loss. Understanding the condition and the roots of the problem can help you empower yourself and stick with your treatment plan.
  • Set realistic goals. Find reasonable, manageable targets that will help you meet your needs and not set you up to fail.
  • Stick to your treatment plan. Exercise and eat properly. If your doctor prescribed medicine, stick with the treatment, and let your doctor know if you have any side effects.
  • Tell your doctor If you find yourself slipping. It’s hard to change lifelong habits, but there may be more than one way to reach your goal. Sometimes the real challenge is finding the habits you can change.
  • Get support. Don’t be afraid to ask family and friends to help you with emotional support.
  • Watch out for your triggers. Sometimes certain triggers can lead you to eat even if you’re not hungry. Whether it’s snacking while you watch a movie or binge eating when you’re stressed, watch out for the things that incite you to eat, and build new habits to keep you healthy.
  • Keep a food journal. Track what you eat in a notebook. This helps you keep yourself accountable, and when you look back on it you can sometimes figure out what does and doesn’t work for you.

When To Contact A Doctor

If you think you may have a weight problem, tell your doctor—especially if you’re concerned about weight-related health problems, such as diabetes, sleep apnea, or high cholesterol.

Questions For Your Doctor

Your primary care doctor can help you with a weight loss plan or refer you to a bariatric physician, or weight loss specialist. As well, you can search online database provided by the American Society of Bariatric Physicians.


Questions For A Doctor

When you go to see your doctor, it’s good to have a list of the questions you’d like to have answered. Take a moment to write down some of the things you want to know. Your questions for your doctor might include some of these:

  • Do I have a weight problem?
  • How serious is it?
  • Am I at risk for health problems related to my weight?
  • Are there warning signs I should watch out for?
  • What steps do you recommend to keep my weight under control?
  • What do you think my weight loss goals should be?
  • Is it safe for me to start an exercise program?
  • Is there anything else I should know about my weight?


Other useful resources to help you learn about weight loss and take charge of your treatment can be found at:

The Obesity Society is “the leading scientific society dedicated to the study of obesity. Since 1982, The Obesity Society has been committed to encouraging research on the causes and treatment of obesity, and to keeping the medical community and public informed of new advances.”

The Obesity Action Coalition (OAC) is a “non-profit organization dedicated to giving a voice to the individual affected by the disease of obesity and helping individuals along their journey toward better health through education, advocacy and support.”

The American Society of Bariatric Physicians offers a searchable directory of doctors who specialize in weight loss.


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