The main treatment for obesity consists of dieting and physical exercise. Diet programs may produce weight loss over the short term, but maintaining this weight loss is frequently difficult and often requires making exercise and a lower food energy diet a permanent part of a person's lifestyle.

In the short-term low carbohydrate diets appear better than low fat diets for weight loss. In the long term; however, all types of low-carbohydrate and low-fat diets appear equally beneficial. A 2014 review found that the heart disease and diabetes risks associated with different diets appear to be similar. Promotion of the Mediterranean diets among the obese may lower the risk of heart disease. Decreased intake of sweet drinks is also related to weight-loss. Success rates of long-term weight loss maintenance with lifestyle changes are low, ranging from 2–20%. Dietary and lifestyle changes are effective in limiting excessive weight gain in pregnancy and improve outcomes for both the mother and the child. Intensive behavioral counseling is recommended in those who are both obese and have other risk factors for heart disease.

Five medications have evidence for long-term use orlistat, lorcaserin, liraglutide, phentermine–topiramate, and naltrexone–bupropion. They result in weight loss after one year ranged from 3.0 to 6.7 kg over placebo. Orlistat, liraglutide, and naltrexone–bupropion are available in both the United States and Europe, whereas lorcaserin and phentermine–topiramate are available only in the United States. European regulatory authorities rejected the latter two drugs in part because of associations of heart valve problems with lorcaserin and more general heart and blood vessel problems with phentermine–topiramate. Orlistat use is associated with high rates of gastrointestinal side effects and concerns have been raised about negative effects on the kidneys. There is no information on how these drugs affect longer-term complications of obesity such as cardiovascular disease or death.

The most effective treatment for obesity is bariatric surgery. The types of procedures include laparoscopic adjustable gastric banding, Roux-en-Y gastric bypass, vertical-sleeve gastrectomy, and biliopancreatic diversion. Surgery for severe obesity is associated with long-term weight loss, improvement in obesity related conditions, and decreased overall mortality. One study found a weight loss of between 14% and 25% (depending on the type of procedure performed) at 10 years, and a 29% reduction in all cause mortality when compared to standard weight loss measures. Complications occur in about 17% of cases and reoperation is needed in 7% of cases. Due to its cost and risks, researchers are searching for other effective yet less invasive treatments including devices that occupy space in the stomach.

Several studies have shown that obese men tend to have a lower sperm count, fewer rapidly mobile sperm and fewer progressively motile sperm compared to normal-weight men.

Obesity in Germany has created a cholesterol problem. High cholesterol is known to cause premature death, angina, heart disease and strokes.

There has been an increase of children with Type 1 diabetes between 1996 and 2011. Diabetics are at higher risk for complications such as heart attack and stroke. In Germany, 600,000 people suffered from diabetes near the end of World War II compared to eight million now.

Obesity can increased risk for secondary diseases such as diabetes, cardiovascular disease, certain cancers and Alzheimer's. Children who get diabetes can expect to lose 10 to 15 years off of their lives. Diabetes also affect the eyes, kidneys and nerves in the legs.

Obesity is a "very strong promoter of cancer." Obesity causes an increased risk for colon cancer and breast cancer.

Obesity in North Africa and the Middle East is a notable health issue. In 2005, the World Health Organization measured that 1.6 billion people were overweight and 400 million were obese. It estimates that by the year 2015, 2.3 billion people will be overweight and 700 million will be obese. The Middle East, including the Arabian Peninsula, Eastern Mediterranean, Turkey and Iran, and North Africa, are no exception to the worldwide increase in obesity. Subsequently, some call this trend the New World Syndrome. The lifestyle changes associated with the discovery of oil and the subsequent increase in wealth is one contributing factor.

Urbanization has occurred rapidly and has been accompanied by new technologies that promote sedentary lifestyles. Due to accessibility of private cars, television, and household appliances, the population as a whole is engaging in less physical activity. The rise in caloric and fat intake in a region where exercise is not a defining part of the culture has added to the overall increased percentages of overweight and obese populations. In addition, women are more likely to be overweight or obese due to cultural norms and perceptions of appropriate female behavior and occupations inside and outside of the home.

Obesity in Mexico is a relatively recent phenomenon, having been widespread since the 1980s with the introduction of processed food into much of the Mexican food market. Prior to that, dietary issues were limited to under and malnutrition, which is still a problem in various parts of the country. Following trends already ongoing in other parts of the world, Mexicans have been foregoing traditional whole grains and vegetables in favor of a diet with more animal products, more fat, and more sugar much of which is a consequence of processed food. It has seen dietary energy intake and rates of overweight and obese people rise with seven out of ten at least overweight and a third clinically obese.

Until the late 20th century, dietary issues in Mexico were solely a question of undernutrition or malnutrition, generally because of poverty and distribution issues. For this reason, obesity was associated with wealth and health, the latter especially in children. Despite changes in the Mexican diet and food distribution, malnutrition still remains problematic in various parts of the country.

Obesity in Germany has been increasingly cited as a major health issue in recent years. The federal government has declared this to be a major issue.

Data released by the World Health Organisation in 2014 showed that while an issue of growing concern, within the European Union, Germany had a lower incidence of overweight and obese adults as a percentage of the total population at 54.8% in comparison with France at 60.7%, Spain at 60.9% or the United Kingdom at 63.4%.

Obesity in the United States has been increasingly cited as a major health issue in recent decades, resulting in diseases such as coronary heart disease that lead to mortality. While many industrialized countries have experienced similar increases, obesity rates in the United States are the highest in the world.

Obesity has continued to grow within the United States. Two of every three American men are considered to be overweight or obese, but the rates for women are far higher. The United States contains one of the highest percentage of obese people in the world. An obese person in America incurs an average of $1,429 more in medical expenses annually. Approximately $147 billion is spent in added medical expenses per year within the United States. This number is suspected to increase approximately $1.24 billion per year until the year 2030.

The United States had the highest rate of obesity within the OECD grouping of large trading economies. From 23% obesity in 1962, estimates have steadily increased. The following statistics comprise adults age 20 and over. The overweight percentages for the overall US population are higher reaching 39.4% in 1997, 44.5% in 2004, 56.6% in 2007, and 63.8% (adults) and 17% (children) in 2008. In 2010, the Centers for Disease Control and Prevention (CDC) reported higher numbers once more, counting 65.7% of American adults as overweight, and 17% of American children, and according to the CDC, 63% of teenage girls become overweight by age 11. In 2013 the Organisation for Economic Co-operation and Development (OECD) found that 57.6% of American citizens were obese. The organization estimates that 3/4 of the American population will likely be overweight or obese by 2020. The latest figures from the CDC as of 2014 show that more than one-third (36.5%) of U.S. adults age 20 and older and 17% of children and adolescents aged 2–19 years were obese. A second study from the National Center for Health Statistics at the CDC showed that 39.6% of US adults age 20 and older were obese as of 2015-2016 (37.9% for men and 41.1% for women).

Obesity has been cited as a contributing factor to approximately 100–400 000 deaths in the United States per year and has increased health care use and expenditures, costing society an estimated $117 billion in direct (preventive, diagnostic, and treatment services related to weight) and indirect (absenteeism, loss of future earnings due to premature death) costs. This exceeds health care costs associated with smoking and accounts for 6% to 12% of national health care expenditures in the United States.

Obesity has been observed throughout human history. Many early depictions of the human form in art and sculpture appear obese. However, it was not until the 20th century that obesity became common — so much so that, in 1997, the World Health Organization (WHO) formally recognized obesity as a global epidemic. Obesity is defined as having a body mass index (BMI) greater than or equal to 30 kg/m, and in June 2013 the American Medical Association classified it as a disease, with much controversy.

In countries of the Organisation for Economic Co-operation and Development (OECD), one child out of five is overweight or obese. Once considered a problem only of high-income countries, obesity rates are rising worldwide. Globally, there are now more people who are obese than who are underweight, a trend observed in every region over the world except parts of sub-Saharan Africa and Asia. In 2013, an estimated 2.1 billion adults were overweight, as compared with 857 million in 1980. Of adults who are overweight, 31% are obese. Increases in obesity have been seen most in urban settings.

Since body fat can be measured in several ways, statistics on the epidemiology of obesity vary between sources. While BMI is the most basic and commonly used indicator of obesity, other measures include waist circumference, waist-to-hip ratio, skinfold thicknesses, and bioelectrical impedance. The rate of obesity increases with age at least up to 50 or 60 years old.

The OECD notes that — given the health, economic, and social consequences of obesity — many countries have built multi-stakeholder networks involving civil society and the business sector in order to devise appropriate public health policies and solutions for obesity prevention.

According to Cleveland Clinic, cultural, social, and environmental factors, among others, all affect eating behaviors.

Many organizations have published reports pertaining to obesity. In 1998, the first US Federal guidelines were published, titled "Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report". In 2006 the Canadian Obesity Network published the "Canadian Clinical Practice Guidelines (CPG) on the Management and Prevention of Obesity in Adults and Children". This is a comprehensive evidence-based guideline to address the management and prevention of overweight and obesity in adults and children.

In 2004, the United Kingdom Royal College of Physicians, the Faculty of Public Health and the Royal College of Paediatrics and Child Health released the report "Storing up Problems", which highlighted the growing problem of obesity in the UK. The same year, the House of Commons Health Select Committee published its "most comprehensive inquiry [...] ever undertaken" into the impact of obesity on health and society in the UK and possible approaches to the problem. In 2006, the National Institute for Health and Clinical Excellence (NICE) issued a guideline on the diagnosis and management of obesity, as well as policy implications for non-healthcare organizations such as local councils. A 2007 report produced by Derek Wanless for the King's Fund warned that unless further action was taken, obesity had the capacity to cripple the National Health Service financially.

Comprehensive approaches are being looked at to address the rising rates of obesity. The Obesity Policy Action (OPA) framework divides measure into 'upstream' policies, 'midstream' policies, 'downstream' policies. 'Upstream' policies look at changing society, 'midstream' policies try to alter individuals' behavior to prevent obesity, and 'downstream' policies try to treat currently afflicted people.

The medical condition of being overweight or obesity is defined as "abnormal or excessive fat accumulation that may impair health". It is measured through the Body Mass Index (BMI), defined as a person's weight, in kilograms, divided by the square of the person's height, in meters. If an individual has a BMI of 25–29, he or she is overweight. Having a BMI of 30 or more means an individual is obese. The greater the BMI, the greater the risk of chronic diseases as a result of obesity. These diseases include cardiovascular diseases, diabetes, musculoskeletal disorders, cancer, and premature death.

Obesity in the United Kingdom is a significant contemporary health concern, with officials stating that it is one of the leading preventable causes of death. In February 2016, Health Secretary Jeremy Hunt described rising rates of childhood obesity as a "national emergency".

Data published as a part of the World Health Organisation (WHO) study in 2014 indicated that 28.1% of adults in the United Kingdom were recognised as clinically obese with a Body Mass Index (BMI) greater than 30. In 2014 62% of adults in England were classified as overweight (a body mass index of 25 or above) or obese, compared to 53% 20 years earlier. More than two-thirds of men and almost six in 10 women are overweight or obese.

Experts have predicted that by the year 2020 one third of the United Kingdom population could be obese. Rising levels of obesity are a major challenge to public health. There are expected to be 11 million more obese adults in the UK by 2030, accruing up to 668,000 additional cases of diabetes mellitus, 461,000 cases of heart disease and stroke, 130,000 cases of cancer, with associated medical costs set to increase by £1.9–2.0B per year by 2030. Adult obesity rates have almost quadrupled in the last 25 years.

For children, data from the Health Survey for England (HSE) conducted in 2014 and examining patterns of overweight and obesity among children aged 2–15, showed that 17% of children were obese and an additional 14% of children were overweight.

Combing three years of data (2012, 2013 and 2014) Public Health England identified Barnsley, South Yorkshire as the local authority with the highest incidence of adult obesity (BMI greater than 30) with 35.1%. Data from the same study revealed that Doncaster, South Yorkshire was the local authority with the highest overall excess weight with 74.8% of adults (16 years and over) with a BMI greater than 25. In previous Public Health England studies based on 2012 data, Tamworth in Staffordshire had been identified as the fattest town in England with a 30.7% obesity rate.

Various groups including government, food and health care professionals have made attempts to highlight and address the causes and growing problem of obesity in the United Kingdom.

In summary, key policy interventions for the prevention of stunting are:

- Improvement in nutrition surveillance activities to identify rates and trends of stunting and other forms of malnutrition within countries. This should be done with an equity perspective, as it is likely that stunting rates will vary greatly between different population groups. The most vulnerable should be prioritized. The same should be done for risk factors such as anemia, maternal under-nutrition, food insecurity, low birth-weight, breastfeeding practices etc. By collecting more detailed information, it is easier to ensure that policy interventions really address the root causes of stunting.

- Political will to develop and implement national targets and strategies in line with evidence-based international guidelines as well as contextual factors.

- Designing and implementing policies promoting nutritional and health well-being of mothers and women of reproductive age. The main focus should be on the 1000 days of pregnancy and first two years of life, but the pre-conception period should not be neglected as it can play a significant role in ensuring the fetus and baby's nutrition.

- Designing and implementing policies promoting proper breastfeeding and complementary feeding practice (focusing on diet diversity for both macro and micronutrients). This can ensure optimal infant nutrition as well as protection from infections that can weaken the child's body. Labor policy ensuring mothers have the chance to breastfeed should be considered where necessary.

- Introducing interventions addressing social and other health determinants of stunting, such as poor sanitation and access to drinking water, early marriages, intestinal parasite infections, malaria and other childhood preventable disease (referred to as “nutrition-sensitive interventions”), as well as the country's food security landscape. Interventions to keep adolescent girls in school can be effective at delaying marriage with subsequent nutritional benefits for both women and babies. Regulating milk substitutes is also very important to ensure that as many mothers as possible breastfeed their babies, unless a clear contraindication is present.

- Broadly speaking, effective policies to reduce stunting require multisectoral approaches, strong political commitment, community involvement and integrated service delivery.

Obesity in India has reached epidemic proportions in the 21st century, with morbid obesity affecting 5% of the country's population. India is following a trend of other developing countries that are steadily becoming more obese. Unhealthy, processed food has become much more accessible following India's continued integration in global food markets. This, combined with rising middle class incomes, is increasing the average caloric intake per individual among the middle class and above income households. Obesity is a major risk factor for cardiovascular disease, NGOs such as the Indian Heart Association have been raising awareness about this issue.

While studying 22 different SNPs near to MC-R gene, scientists have identified a SNP (single nucleotide polymorphism) named rs12970134 to be mostly associated with waist circumference. In this study more than two thousand individuals of Indian origin participated and the aforementioned SNP is highly prevalent in this group.

Internationally, a BMI over 25 kg/m2 is considered overweight. Due to genetic tendency of Indians towards abdominal obesity and its associated risk of related lifestyle diseases like Diabetes & Heart Disease, Guidelines for diagnosis of obesity and abdominal obesity for India have been published in JAPI (2009) that a BMI over 23 kg/m2 is considered overweight. Further definitions: Normal BMI: 18.0-22.9 kg/m2, Overweight: 23.0-24.9 kg/m2, Obesity: >25 kg/m2.

Ensuring proper nutrition of pregnant and lactating mothers is essential. Achieving so by helping women of reproductive age be in good nutritional status at conception is an excellent preventive measure. A focus on the pre-conception period has recently been introduced as a complement to the key phase of the 1000 days of pregnancy and first two years of life. An example of this is are attempts to control anemia in women of reproductive age. A well-nourished mother is the first step of stunting prevention, decreasing chances of the baby being born of low birth-weight, which is the first risk factor for future malnutrition.

After birth, in terms of interventions for the child, early initiation of breastfeeding, together with exclusive breastfeeding for the first 6 months, are pillars of stunting prevention. Introducing proper complementary feeding after 6 months of age together with breastfeeding until age 2 is the next step.

This is a list of the states of India ranked in order of percentage of people who are overweight or obese, based on data from the 2007 National Family Health Survey.

Cardiovascular disease is the principal cause of death in the UAE, constituting 28 percent of total deaths; other major causes are accidents and injuries, malignancies, and congenital anomalies.

In 1985 the UAE established a national program to prevent transmission of acquired immune deficiency syndrome (AIDS) and to control its entry into the country. According to World Health Organization estimates, in 2002−3 fewer than 1,000 people in the UAE were living with human immunodeficiency virus (HIV)/AIDS.

In Egypt, according to data from the 2016 Global Burden of Disease study, overweight and obesity (as measured by high BMI) was the country's leading risk factor driving the most death and disability combined.

Timed light exposure can be effective to help people match their circadian rhythms with the expected cycle at their destination; it requires strict adherence to timing. Light therapy is a popular method used by professional athletes to reduce jet lag. Special glasses, usually battery-driven, provide light to the eyes, thus inhibiting the production of melatonin in the brain. Timed correctly, the light may contribute to an advance or delay of the circadian phase to that which will be needed at the destination. The glasses may be used on the plane or even before users leave their departure city.

Timed melatonin administration may be effective in reducing jet lag symptoms. The benefit of using melatonin is likely to be greater for eastward flights than for westward ones because for most people it is easier to delay than to advance the circadian rhythm. There remain issues regarding the appropriate timing of melatonin use in addition to the legality of the substance in certain countries. How effective it may actually be is also questionable. For athletes, anti-doping agencies may prohibit or limit its use.

Timing of exercise and food consumption have also been suggested as remedies, though their applicability in humans and practicality for most travellers are not certain, and no firm guidelines exist. There are very little data supporting the use of diet to adjust to jet lag. While there are data supporting the use of exercise, the intensity of exercise that may be required is significant, and possibly difficult to maintain for non-athletes. These strategies may be used both before departure and after landing. Individuals may differ in their susceptibility to jet lag and in how quickly they can adjust to new sleep-wake schedules.

Short-acting sleep medications can be used to improve sleep quality and timing, and stimulating substances such as caffeine can be used to promote wakefulness, though research results on their success at adapting to jet lag are inconsistent.

For time changes of fewer than three hours, jet lag is unlikely to be a concern, and if travel is for short periods (three days or fewer) retaining a "home schedule" may be better for most people. Sleeping on the plane is only advised if it is within the destination's normal sleep time.

Travelling west causes fewer problems than travelling east, and it is usually sufficient to seek exposure to light during the day and avoid it at night.