Weight loss: Obesity, diets, and calories


People with obesity may have a higher risk of certain health complications. For this reason, people with obesity may want to lose weight. Making dietary changes, exercising, and setting realistic targets are some ways of losing weight.

People generally gain weight by consuming more energy than they burn, so consuming fewer calories, or energy, can help.

However, other factors play a role, such as genetics, metabolism, hormones, the type of food a person eats, their body type, and lifestyle.

This article reviews some reasons to lose weight, the most effective methods, and medical interventions.

Today, health experts consider obesity an epidemic.

Every year, at least 2.8 million people die from complications related to overweight and obesity, states the World Health Organization (WHO).

According to the Centers for Disease Control and Prevention (CDC), the prevalence of obesity in U.S. adults was 41.9% from 2017–2020.

Obesity affects some groups more than others. According to the CDC, the following groups had obesity from 2017–2020 in the United States:

  • 49.9% of Black adults
  • 45.6% of Hispanic adults
  • 41.4% of white adults
  • 16.1% of Asian adults

The health risks of overweight and obesity include:

If a person has overweight or obesity, some reasons to lose weight include:

Many diet plans make weight loss claims. It can be difficult to know if they are true.

Some are evidence-based, safe, and effective, but others are not. Many healthcare professionals, dietitians, and nutritionists agree that the best results tend to come from combining a sustainable, balanced diet with physical activity, especially in the long term.

Some diets to consider include the Mediterranean diet and DASH diet.

These diets prioritize:

  • fruits
  • vegetables
  • lean proteins
  • whole grains
  • healthy fats

They minimize:

  • added sugars
  • refined grains
  • trans fats
  • ultra-processed foods

However, it is not always possible to know how effective a diet will be for losing weight.

Many factors determine how many calories a person should eat per day to lose weight.

Some of these factors include:

  • desired weight loss
  • desired speed of weight loss
  • age
  • sex

According to the Dietary Guidelines for Americans 2020–2025, below are the daily calorie recommendations for adults based on activity level:

Daily recommended calorie consumption for males

Daily recommended calorie consumption for females

If a person wants to lose weight, consuming fewer calories than the amounts listed above may help. It is important to follow a nutritious, well-balanced diet.

A person should check with a dietitian, nutritionist, or primary care doctor, if possible, before changing their diet.

A healthcare professional can ensure the person’s carbohydrate, protein, and fat ratios are suitable for good health.

A healthy, sustainable meal plan prioritizes nutrients. A poor diet and malnutrition can occur regardless of calories. A poor diet can also lead to a low mood.

When a person has reached their target body weight, they can gradually increase their daily intake of calories until they maintain their weight.

A person can successfully manage their body weight by combining a well-balanced diet with regular physical activity.

Getting adequate, quality sleep may also help a person manage their weight. A 2018 review of research states that impaired sleep may lead to enhanced appetite, cravings, and decreased motivation for physical activity.

There are many ways a person can manage their weight after losing weight. Some helpful options include:

  • Avoiding restrictive diets: Too much calorie restriction can slow the metabolism and alter hormones that regulate appetite. This can cause weight gain.
  • Getting regular exercise: According to a 2021 review, exercising for 225–420 minutes per week is associated with improved weight maintenance.
  • Eating more protein: Protein can make a person feel full and reduce hunger.
  • Considering carbs: A low carb diet may help with weight loss maintenance.

Weight loss efforts alongside mental health care and self-care may improve a person’s outcome.

A 2021 study with 60 women ages 20–30 years found that those with an individualized diet plan paired with goal-oriented psychotherapy saw more weight loss over the long term.

Study authors state the primary cause of obesity is the inability to control overeating, so obesity should be treated as an eating disorder.

Supporting weight loss with psychotherapy can help mitigate the negative effects of issues arising from traditional diets.

Anecdotally, some people claim the following supplements help them lose weight:

  • omega-3 products and fish oils
  • chitosan, derived from shellfish
  • green tea extracts
  • some Chinese herbs
  • bitter orange extract

However, according to the National Center for Complementary and Integrative Health (NCCIH), these supplements are ineffective for weight loss or weight management. They are likely to cause negative side effects.

Ephedra, which was once an ingredient in some weight loss supplements, is now banned because of safety concerns.

Further concerns include the sale of “fat burners” that do not have approval from the Food and Drug Administration (FDA).

Because the FDA does not regulate the quality or purity of supplements as it does for medications, some herbal supplements may not contain exactly what the label says.

The NCCIH points out that approaches focusing on the mind and the body may help a person manage their weight.

Examples include:

The organization recommends finding a qualified and experienced instructor for these activities.

Bariatric surgery, also known as weight loss surgery, is a surgical procedure for people whose body mass index (BMI) is high enough that it puts them at risk of serious complications.

A doctor may recommend bariatric surgery if other weight loss strategies have not worked.

The procedure involves either reducing the size of the stomach with a gastric band or surgically removing part of the stomach.

In some cases, a doctor may recommend a type of gastric bypass surgery in which the small intestine is rerouted to a small stomach pouch.

This surgery considerably reduces a person’s appetite. They cannot absorb or digest food as fully as before.

Bariatric surgery can be an effective way to lose weight for people with severe obesity.

The procedure can also treat type 2 diabetes and reduce cardiometabolic risk.

It is important for a person to aim for a body weight compatible with their height, sex, and age.

Learn how to calculate BMI and other ways to assess body weight.

In some cases, losing weight may create problems.

Weight loss happens when a person exerts more energy than they consume. This is called a negative energy balance. The body seeks stores of energy, starting with fat, to compensate for the shortfall.

If the body has little fat, more muscle and lean tissue are used for energy. This can lead to further health problems.

These health issues include:

A severe loss of body mass can be life threatening.

A person experiencing unexplained weight loss should talk with a healthcare professional to determine the cause and get treatment if needed.

Below are some commonly asked questions about how a person can lose weight.

How can a person with obesity lose weight fast?

The CDC recommends a person lose 1–2 pounds per week for sustainable weight loss. This is because quick weight loss is unlikely to be maintained, and weight regain may occur.

A person with obesity can consider getting 150 minutes of moderate intensity physical activity per week and strengthening activities at least 2 days per week.

To lose weight, the United Kingdom’s National Health Service suggests aiming to get five portions of fruit and vegetables a day, swapping sugary drinks for water, and avoiding or limiting foods high in added sugar, such as highly processed foods.

How long does it take a person with obesity to lose 20 pounds?

The CDC recommends losing 1–2 pounds per week. This is because people are more likely to avoid weight regain with gradual, steady weight loss.

With this guideline in mind, a person with obesity could lose up to 20 pounds in 10 weeks.

How much weight can I lose in a month if I am obese?

The CDC recommends losing 1–2 pounds per week for sustainable weight loss.

Considering this approach, a person with obesity could lose up to 8 pounds in 1 month.

If a person wants to lose weight, there are many factors to consider, such as age, sex, diet, activity level, and health conditions.

Reducing calories, getting regular physical activity, eating a nutrient-dense and balanced diet, and getting quality sleep can help people lose weight.

In some cases, a person may benefit from surgery, such as bariatric surgery, to lose weight.

However, too much weight loss can be problematic for a person’s health.

To avoid complications and support them in managing their weight, a person can talk with a healthcare professional before changing their diet and exercise routine.


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