Table of ContentsView AllTable of ContentsDefintionLifestyle CausesGenetic CausesBiological/Medical CausesSocial CausesNext in Obesity GuideHow Obesity Is Diagnosed
Table of ContentsView All
View All
Table of Contents
Defintion
Lifestyle Causes
Genetic Causes
Biological/Medical Causes
Social Causes
Next in Obesity Guide
Read on to learn more about obesity and its causes.
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Defining Obesity
For example, a very fit and muscular person will have a higher BMI because muscle weighs more than fat, and they won’t necessarily have obesity or be at a high risk of obesity-related complications.
BMI is a dated, flawed measure. It does not take into account factors such asbody composition, ethnicity, sex, race, and age. Even though it is abiased measure, BMI is still widely used in the medical community because it’s an inexpensive and quick way to analyze a person’s potential health status and outcomes.
There areother ways to measure body fat, such as dual-energy X-ray absorption (DEXA), underwater weighing, and bioelectrical impedance. However, these methods aren’t as widely available as BMI measurements. Measuring skin fold thickness with calipers is an alternative method, but it can be difficult to standardize.BMI is a simpler and easily measured way to screen for obesity, but it is still a problematic measurement that may need to be re-interpreted in the proper context for individuals.
Lifestyle Related Causes of Obesity
Obesity is usually blamed on behaviors of taking in too many calories while not burning enough calories. While there is truth that not burning calories you eat over time leads to weight gain, this simplistic explanation doesn’t account for the role of biology and environment. Not everyone absorbs, stores, and expends energy the exact same way, and there are variations in hormones related to metabolism in individuals.
Researchers are still discovering the exact causes and contributors to obesity. However, there is no denying that certain lifestyle habits have a great impact on obesity. The imbalance of food intake and activity is believed to be one of the biggest contributors to weight gain.
Diet
Diet is a major contributor to obesity. Eating high-calorie foods and a diet high in saturated fats and refined sugars, especially processed foods has been linked to weight gain and obesity. A study looking at worldwide populations found that increased soda consumption in adolescents was associated with a higher prevalence of obesity.
It’s not hard to see why since one 12-ounce can of soda contains about 40 grams (almost 10 teaspoons!) of sugar. Processed snack foods are loaded with a combination of salt and saturated fats or refined sugars, a high-calorie combination that is suggested to alter appetite signals and lead to addiction-like andwithdrawalbehaviors.
Activity
Another major contributor to obesity is a sedentary lifestyle. Spending more time sitting burns less calories and means less time is spent doing physical activity that would burn more calories. Asedentary lifestyleis linked to obesity and other chronic conditions like diabetes, heart disease, and high blood pressure.
On the other hand, regular physical activity, such as moderate-intensity exercises like brisk walking, jogging, swimming, or aerobic sports has many health benefits, including helping maintain a target weight.
Sleep
The quality and duration of sleep also appears to play a role in obesity. Sleeping less than 7 hours per night is linked to higher body weight and obesity, which researchers suggest may be related to the effect sleep deprivation has onappetite-related hormones.Furthermore, evidence suggests an association of weight gain with circadian misalignment, which is the body being awake during times when the body’s sleep/wake cycle, such as in people doing night-shift work.
Stress
Stress levelsover time can also impact weight gain and contribute to obesity. Chronic stress, which may be due to any number of causes, is associated with obesity.Stress increases the amount of stress hormone (cortisol) in the body, which, over time, can lead to weight gain.Furthermore, the way people cope with stress can also affect their weight in some cases. For example, binge-eating (or “stress-eating”) contributes to excess calories and potential weight gain.
Obesity and Depression: Is There a Connection?
Genetic Causes of Obesity
If your parents are obese, you’re more likely to have it, too. This is partly related to lifestyle factors that tend to be similar to family members. However, genetics also play a role in obesity. Researchers have discovered many genetic variations that can increase the susceptibility to obesity. These include mutations in appetite regulation and energy balance, such as proteins and hormones that help us feel hungry or full.
Prader-Willi syndromeis a rare genetic condition that causes insatiable appetite in affected children. This leads to overeating and obesity.Bardet-Biedl syndrome is another rare genetic condition affecting the eyes that also causes obesity starting in childhood.
Biologic and Medical Contributors to Obesity
Several medical conditions can contribute to excess body weight and obesity. Many of these are related to hormones involved in metabolism and appetite. And the gut microbiome is becoming increasingly recognized for its impact on obesity.
Hypothyroidism
Hypothyroidismis a condition where there are not enough thyroid hormones circulating in the blood. Thyroid hormones are involved in many body processes, and are important in weight, energy levels, growth of skin, hair and nails, and digestion, among other things.
When your body doesn’t have enough thyroid hormones, you can expect to have low energy levels and gain weight, which can lead to obesity. However, the American Thyroid Association notes that much of the weight gain in hypothyroidism is related to salt and water retention, with an expected weight gain of up to 10 pounds.
Cushing’s Syndrome
Polycystic Ovarian Syndrome
Polycystic ovarian syndrome (PCOS) is a syndrome resulting in cysts on the ovaries as well as hormonal changes, such asinsulin resistanceand excessandrogen hormones. There is a definite link between PCOS and obesity. Researchers think this relationship is due to genetic and hormonal factors.
The Gut Microbiome
Studies suggest that the typical Western diet with foods high in saturated fats and refined sugars may also promote obesity through the effects this diet has on the gut microbiome.
Social Drivers of Obesity
In addition to the biologic and behavioral causes of obesity discussed above, there aresocial driversof obesity. While these social drivers can impact behavior, it’s important to recognize that
The following are social factors related to increased risk of obesity:
Summary
Obesity is a common condition that has many causes spanning behavioral, biologic, and environmental. Diet and physical activity are major contributors, but stress and sleep also play a role. Biologic factors such as genetics and medical conditions affect appetite and satiety as well as energy balance and metabolism. Lastly, social and environmental factors play a role that can be beyond an individual’s immediate control.
23 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Heart, Lung, and Blood Institute.What are overweight and obesity?Centers for Disease Control and prevention.Body mass index: Considerations for practitioners.National Institute of Child Health and Human Development.What causes obesity and overweight?Hu H, Song J, MacGregor GA, He FJ.Consumption of soft drinks and overweight and obesity among adolescents in 107 countries and regions.JAMA Netw Open.2023;6(7):e2325158. doi:10.1001/jamanetworkopen.2023.25158Parnarouskis L, Leventhal AM, Ferguson SG, Gearhardt AN.Withdrawal: A key consideration in evaluating whether highly processed foods are addictive.Obes Rev. 2022;23(11):e13507. doi:10.1111/obr.13507Moris JM, Heinold C, Blades A, Koh Y.Nutrient-based appetite regulation.J Obes Metab Syndr. 2022;31(2):161-168. doi:10.7570/jomes22031Silveira EA, Mendonça CR, Delpino FM, et al.Sedentary behavior, physical inactivity, abdominal obesity and obesity in adults and older adults: A systematic review and meta-analysis.Clin Nutr ESPEN. 2022;50:63-73. doi:10.1016/j.clnesp.2022.06.001Cleven L, Krell-Roesch J, Nigg CR, et al.The association between physical activity with incident obesity, coronary heart disease, diabetes and hypertension in adults: a systematic review of longitudinal studies published after 2012.BMC Public Health.2020;20(1):726. doi:10.1186/s12889-020-08715-4Cooper CB, Neufeld EV, Dolezal BA, Martin JL.Sleep deprivation and obesity in adults: a brief narrative review.BMJ Open Sport Exerc Med. 2018;4(1):e000392. doi:10.1136/bmjsem-2018-000392Chaput JP, McHill AW, Cox RC, et al.The role of insufficient sleep and circadian misalignment in obesity.Nat Rev Endocrinol. 2023;19(2):82-97. doi:10.1038/s41574-022-00747-7Cuevas AG, Chen R, Thurber KA, Slopen N, Williams DR.Psychosocial stress and overweight and obesity: Findings from the Chicago Community Adult Health Study.Ann Behav Med. 2019;53(11):NP. doi:10.1093/abm/kaz008Goens D, Virzi NE, Jung SE, Rutledge TR, Zarrinpar A.Obesity, chronic stress, and stress reduction.Gastroenterology Clinics of North America. 2023;52(2):347-362. doi:10.1016/j.gtc.2023.03.009Mahmoud R, Kimonis V, Butler MG.Genetics of obesity in humans: A clinical review.Int J Mol Sci. 2022;23(19):11005. doi:10.3390/ijms231911005MedlinePlus.Prader-Willi syndrome.MedlinePlus.Bardet-Biedl syndrome.Endocrine Society.Thyroid and parathyroid hormones.American Thyroid Association.Thyroid and weight.National Institute of Diabetes and Digestive and Kidney Diseases.Cushing’s syndrome.Barber TM, Hanson P, Weickert MO, Franks S.Obesity and polycystic ovary syndrome: Implications for pathogenesis and novel management strategies.Clin Med Insights Reprod Health. 2019;13:1179558119874042. doi:10.1177/1179558119874042National Institute of Environmental Health Sciences.Microbiome.Cheng Z, Zhang L, Yang L, Chu H.The critical role of gut microbiota in obesity.Front Endocrinol (Lausanne). 2022;13:1025706. doi:10.3389/fendo.2022.1025706Singh RK, Chang HW, Yan D, et al.Influence of diet on the gut microbiome and implications for human health.J Transl Med. 2017;15(1):73. doi:10.1186/s12967-017-1175-yLee A, Cardel M, Donahoo WT.Social and environmental factors influencing obesity. [Updated 2019 Oct 12]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-.
23 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Heart, Lung, and Blood Institute.What are overweight and obesity?Centers for Disease Control and prevention.Body mass index: Considerations for practitioners.National Institute of Child Health and Human Development.What causes obesity and overweight?Hu H, Song J, MacGregor GA, He FJ.Consumption of soft drinks and overweight and obesity among adolescents in 107 countries and regions.JAMA Netw Open.2023;6(7):e2325158. doi:10.1001/jamanetworkopen.2023.25158Parnarouskis L, Leventhal AM, Ferguson SG, Gearhardt AN.Withdrawal: A key consideration in evaluating whether highly processed foods are addictive.Obes Rev. 2022;23(11):e13507. doi:10.1111/obr.13507Moris JM, Heinold C, Blades A, Koh Y.Nutrient-based appetite regulation.J Obes Metab Syndr. 2022;31(2):161-168. doi:10.7570/jomes22031Silveira EA, Mendonça CR, Delpino FM, et al.Sedentary behavior, physical inactivity, abdominal obesity and obesity in adults and older adults: A systematic review and meta-analysis.Clin Nutr ESPEN. 2022;50:63-73. doi:10.1016/j.clnesp.2022.06.001Cleven L, Krell-Roesch J, Nigg CR, et al.The association between physical activity with incident obesity, coronary heart disease, diabetes and hypertension in adults: a systematic review of longitudinal studies published after 2012.BMC Public Health.2020;20(1):726. doi:10.1186/s12889-020-08715-4Cooper CB, Neufeld EV, Dolezal BA, Martin JL.Sleep deprivation and obesity in adults: a brief narrative review.BMJ Open Sport Exerc Med. 2018;4(1):e000392. doi:10.1136/bmjsem-2018-000392Chaput JP, McHill AW, Cox RC, et al.The role of insufficient sleep and circadian misalignment in obesity.Nat Rev Endocrinol. 2023;19(2):82-97. doi:10.1038/s41574-022-00747-7Cuevas AG, Chen R, Thurber KA, Slopen N, Williams DR.Psychosocial stress and overweight and obesity: Findings from the Chicago Community Adult Health Study.Ann Behav Med. 2019;53(11):NP. doi:10.1093/abm/kaz008Goens D, Virzi NE, Jung SE, Rutledge TR, Zarrinpar A.Obesity, chronic stress, and stress reduction.Gastroenterology Clinics of North America. 2023;52(2):347-362. doi:10.1016/j.gtc.2023.03.009Mahmoud R, Kimonis V, Butler MG.Genetics of obesity in humans: A clinical review.Int J Mol Sci. 2022;23(19):11005. doi:10.3390/ijms231911005MedlinePlus.Prader-Willi syndrome.MedlinePlus.Bardet-Biedl syndrome.Endocrine Society.Thyroid and parathyroid hormones.American Thyroid Association.Thyroid and weight.National Institute of Diabetes and Digestive and Kidney Diseases.Cushing’s syndrome.Barber TM, Hanson P, Weickert MO, Franks S.Obesity and polycystic ovary syndrome: Implications for pathogenesis and novel management strategies.Clin Med Insights Reprod Health. 2019;13:1179558119874042. doi:10.1177/1179558119874042National Institute of Environmental Health Sciences.Microbiome.Cheng Z, Zhang L, Yang L, Chu H.The critical role of gut microbiota in obesity.Front Endocrinol (Lausanne). 2022;13:1025706. doi:10.3389/fendo.2022.1025706Singh RK, Chang HW, Yan D, et al.Influence of diet on the gut microbiome and implications for human health.J Transl Med. 2017;15(1):73. doi:10.1186/s12967-017-1175-yLee A, Cardel M, Donahoo WT.Social and environmental factors influencing obesity. [Updated 2019 Oct 12]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
National Heart, Lung, and Blood Institute.What are overweight and obesity?Centers for Disease Control and prevention.Body mass index: Considerations for practitioners.National Institute of Child Health and Human Development.What causes obesity and overweight?Hu H, Song J, MacGregor GA, He FJ.Consumption of soft drinks and overweight and obesity among adolescents in 107 countries and regions.JAMA Netw Open.2023;6(7):e2325158. doi:10.1001/jamanetworkopen.2023.25158Parnarouskis L, Leventhal AM, Ferguson SG, Gearhardt AN.Withdrawal: A key consideration in evaluating whether highly processed foods are addictive.Obes Rev. 2022;23(11):e13507. doi:10.1111/obr.13507Moris JM, Heinold C, Blades A, Koh Y.Nutrient-based appetite regulation.J Obes Metab Syndr. 2022;31(2):161-168. doi:10.7570/jomes22031Silveira EA, Mendonça CR, Delpino FM, et al.Sedentary behavior, physical inactivity, abdominal obesity and obesity in adults and older adults: A systematic review and meta-analysis.Clin Nutr ESPEN. 2022;50:63-73. doi:10.1016/j.clnesp.2022.06.001Cleven L, Krell-Roesch J, Nigg CR, et al.The association between physical activity with incident obesity, coronary heart disease, diabetes and hypertension in adults: a systematic review of longitudinal studies published after 2012.BMC Public Health.2020;20(1):726. doi:10.1186/s12889-020-08715-4Cooper CB, Neufeld EV, Dolezal BA, Martin JL.Sleep deprivation and obesity in adults: a brief narrative review.BMJ Open Sport Exerc Med. 2018;4(1):e000392. doi:10.1136/bmjsem-2018-000392Chaput JP, McHill AW, Cox RC, et al.The role of insufficient sleep and circadian misalignment in obesity.Nat Rev Endocrinol. 2023;19(2):82-97. doi:10.1038/s41574-022-00747-7Cuevas AG, Chen R, Thurber KA, Slopen N, Williams DR.Psychosocial stress and overweight and obesity: Findings from the Chicago Community Adult Health Study.Ann Behav Med. 2019;53(11):NP. doi:10.1093/abm/kaz008Goens D, Virzi NE, Jung SE, Rutledge TR, Zarrinpar A.Obesity, chronic stress, and stress reduction.Gastroenterology Clinics of North America. 2023;52(2):347-362. doi:10.1016/j.gtc.2023.03.009Mahmoud R, Kimonis V, Butler MG.Genetics of obesity in humans: A clinical review.Int J Mol Sci. 2022;23(19):11005. doi:10.3390/ijms231911005MedlinePlus.Prader-Willi syndrome.MedlinePlus.Bardet-Biedl syndrome.Endocrine Society.Thyroid and parathyroid hormones.American Thyroid Association.Thyroid and weight.National Institute of Diabetes and Digestive and Kidney Diseases.Cushing’s syndrome.Barber TM, Hanson P, Weickert MO, Franks S.Obesity and polycystic ovary syndrome: Implications for pathogenesis and novel management strategies.Clin Med Insights Reprod Health. 2019;13:1179558119874042. doi:10.1177/1179558119874042National Institute of Environmental Health Sciences.Microbiome.Cheng Z, Zhang L, Yang L, Chu H.The critical role of gut microbiota in obesity.Front Endocrinol (Lausanne). 2022;13:1025706. doi:10.3389/fendo.2022.1025706Singh RK, Chang HW, Yan D, et al.Influence of diet on the gut microbiome and implications for human health.J Transl Med. 2017;15(1):73. doi:10.1186/s12967-017-1175-yLee A, Cardel M, Donahoo WT.Social and environmental factors influencing obesity. [Updated 2019 Oct 12]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-.
National Heart, Lung, and Blood Institute.What are overweight and obesity?
Centers for Disease Control and prevention.Body mass index: Considerations for practitioners.
National Institute of Child Health and Human Development.What causes obesity and overweight?
Hu H, Song J, MacGregor GA, He FJ.Consumption of soft drinks and overweight and obesity among adolescents in 107 countries and regions.JAMA Netw Open.2023;6(7):e2325158. doi:10.1001/jamanetworkopen.2023.25158
Parnarouskis L, Leventhal AM, Ferguson SG, Gearhardt AN.Withdrawal: A key consideration in evaluating whether highly processed foods are addictive.Obes Rev. 2022;23(11):e13507. doi:10.1111/obr.13507
Moris JM, Heinold C, Blades A, Koh Y.Nutrient-based appetite regulation.J Obes Metab Syndr. 2022;31(2):161-168. doi:10.7570/jomes22031
Silveira EA, Mendonça CR, Delpino FM, et al.Sedentary behavior, physical inactivity, abdominal obesity and obesity in adults and older adults: A systematic review and meta-analysis.Clin Nutr ESPEN. 2022;50:63-73. doi:10.1016/j.clnesp.2022.06.001
Cleven L, Krell-Roesch J, Nigg CR, et al.The association between physical activity with incident obesity, coronary heart disease, diabetes and hypertension in adults: a systematic review of longitudinal studies published after 2012.BMC Public Health.2020;20(1):726. doi:10.1186/s12889-020-08715-4
Cooper CB, Neufeld EV, Dolezal BA, Martin JL.Sleep deprivation and obesity in adults: a brief narrative review.BMJ Open Sport Exerc Med. 2018;4(1):e000392. doi:10.1136/bmjsem-2018-000392
Chaput JP, McHill AW, Cox RC, et al.The role of insufficient sleep and circadian misalignment in obesity.Nat Rev Endocrinol. 2023;19(2):82-97. doi:10.1038/s41574-022-00747-7
Cuevas AG, Chen R, Thurber KA, Slopen N, Williams DR.Psychosocial stress and overweight and obesity: Findings from the Chicago Community Adult Health Study.Ann Behav Med. 2019;53(11):NP. doi:10.1093/abm/kaz008
Goens D, Virzi NE, Jung SE, Rutledge TR, Zarrinpar A.Obesity, chronic stress, and stress reduction.Gastroenterology Clinics of North America. 2023;52(2):347-362. doi:10.1016/j.gtc.2023.03.009
Mahmoud R, Kimonis V, Butler MG.Genetics of obesity in humans: A clinical review.Int J Mol Sci. 2022;23(19):11005. doi:10.3390/ijms231911005
MedlinePlus.Prader-Willi syndrome.
MedlinePlus.Bardet-Biedl syndrome.
Endocrine Society.Thyroid and parathyroid hormones.
American Thyroid Association.Thyroid and weight.
National Institute of Diabetes and Digestive and Kidney Diseases.Cushing’s syndrome.
Barber TM, Hanson P, Weickert MO, Franks S.Obesity and polycystic ovary syndrome: Implications for pathogenesis and novel management strategies.Clin Med Insights Reprod Health. 2019;13:1179558119874042. doi:10.1177/1179558119874042
National Institute of Environmental Health Sciences.Microbiome.
Cheng Z, Zhang L, Yang L, Chu H.The critical role of gut microbiota in obesity.Front Endocrinol (Lausanne). 2022;13:1025706. doi:10.3389/fendo.2022.1025706
Singh RK, Chang HW, Yan D, et al.Influence of diet on the gut microbiome and implications for human health.J Transl Med. 2017;15(1):73. doi:10.1186/s12967-017-1175-y
Lee A, Cardel M, Donahoo WT.Social and environmental factors influencing obesity. [Updated 2019 Oct 12]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-.
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