Causes of Obesity By Yasmine Ali, MD - Reviewed by a board-certified physician. Updated September 30, 2016 A number of causes and contributing factors for obesity have now been identified. The vast majority of them fall under the category of dietary and lifestyle choices, but a few may have a biological basis, such as an underlying medical condition or a specific genetic link. Becoming more informed about all of the possibilities can help you prevent obesity and lose excess weight.Dietary Causes: SugarOf all the causes of obesity, the overconsumption of added sugar has been singled out by many experts as the most direct causal factor to the long-term development of obesity. Note that the term “added sugar” refers to and includes all sugars that are added to food, rather than those that occur naturally.It has been reported that the average American consumes 22 teaspoons of sugar a day. Given that the American Heart Association recommends that the intake of added sugar not exceed six teaspoons daily for women and nine teaspoons daily for men, it is easy to see how added sugar leads the charge when it comes to major causes of the obesity and diabetes epidemics. Article Are Energy Drinks Bad for You? List 5 Signs You May Be at Risk for Obesity Part of the problem when it comes to added sugars is that added sugar goes by many names. So, unless you are reading the ingredients label carefully, you may not realize how many different kinds of sugar have been added to what you’re eating or drinking.Food manufacturers have found many different methods and sources by which to add sugar to foods ranging from ketchup to cereal to soft drinks, so look for the following on labels: any ingredient ending in “-ose” (such as maltose, dextrose, sucrose, fructose, lactose, high fructose corn syrup), molasses, cane sugar, corn sweetener, evaporated cane juice, raw sugar, syrup, and fruit juice concentrates. Major sources of added sugars in our diets are soft drinks, candy, cakes, cookies, pies, fruit drinks, dairy desserts and milk products (such as ice cream and sweetened yogurt), and cereals. Most sweetened beverages and fruit drinks contain so much added sugar, in fact, that they have been referred to as “liquid sugar” by some experts.Dietary Causes: CaloriesWhile prior thinking on causes of obesity has often focused on "calories in, calories out," meaning consuming excess calories without burning them leads to weight gain, we now know that all calories are not created equal.Calories that come from nutritious sources such as whole fruits and vegetables, for instance, are clearly healthier for you than the same number of calories that come from refined sweets like candy or other desserts. The latter are thus known as "empty calories," and the unhealthy foods that provide them are known as "calorie-dense" foods.Such calorie-dense foods—sugared beverages, refined carbohydrates, and potato chips, among many others—are also high in sugar, unhealthy fat, and/or salt. Article Disparities in Obesity Article The Case for Home-Cooked Meals Dietary Causes: Saturated FatIt is important to recognize that there are both "good fats" and "bad fats." In the latter category fall saturated fats and trans fats. While the FDA has banned trans fats from the U.S. food market, saturated fats still abound and are found most commonly in animal products such as red meat and dairy.Consumption of saturated fat has been linked to a higher risk of cardiovascular disease and, given that foods that are high in saturated fat are often calorie-dense, this likely plays a role in the development of obesity as well.The "good fats," on the other hand, are the mono- and polyunsaturated fats, such as those found in olive oil, avocados, and tree nuts. Consumption of these healthy fats has been found to result in a lower risk of heart disease and stroke without any extra weight gain.In fact, these healthy fats form an important part of the Mediterranean Diet, which rigorous research has found to be one of the healthiest diets in the world when it comes to preventing cardiovascular disease. Other Dietary CausesThere are other dietary habits that put you at risk for obesity as well. One such diet that has been linked to not only obesity but to heart disease and stroke is the Southern-style diet typical of the southeastern United States.The American South, as a region overall, has also repeatedly been found to have the highest levels of obesity and diabetes, both of which are risk factors for stroke and cardiovascular disease. And researchers have found that eating primarily fried foods, as is common in the South, confers an extremely high risk of heart attack and stroke, not to mention obesity.Other dietary factors that have been associated with a higher risk of obesity, other than the above, include not getting enough whole fruits and vegetables in the daily diet and preparing meals at home less than seven times per week.Simple Dietary Changes You Can MakeGiven the known dietary causes of obesity, there are simple changes you can make to your eating habits that will help you lose weight and prevent obesity. Article Trans Fats: Devil in Disguise? Article The Sugar You're Eating Without Even Knowing It Sip WiselyFirst and foremost, eliminate all sugared beverages from your diet. Make water your go-to beverage; unsweetened tea and coffee are fine, too. Avoid energy drinks or sports drinks, which not only contain an overwhelming amount of added sugar, but have been shown (in the case of energy drinks) to pose potential dangers to the cardiovascular system.Avoid SweetenersIf you feel you must use a sweetener, opt for a small amount of honey, which is a natural alternative and has been shown to have antimicrobial properties. Artificial sweeteners are to be avoided, as those have been linked to obesity and diabetes.Get CookingPrepare a home-cooked meal whenever possible. We already know that we as a nation dine out too much and too often, and the consumption of fast food, in particular, has been linked to the obesity epidemic.Studies that have looked at the frequency of home meal preparation have found that both men and women who prepared meals at home were less likely to gain weight. They were also less likely to develop type 2 diabetes.Gravitate Towards Plant-Based FoodsEating a plant-based diet has been associated with greater overall health and much lower rates of obesity. To achieve this, fill your plate with whole vegetables and fruits at every meal. For snacks, eat unsalted nuts such as almonds, cashews, walnuts, and pistachios (all associated with heart health). Go easy (or eliminate altogether) protein sources that are heavy in saturated fats, such as red meat and dairy.Fruits and vegetables constitute low-calorie foods. A report by the World Health Organization (WHO) states that there is convincing evidence that eating fruits and vegetables decreases the risk for obesity.Compared to high-calorie foods, fruits and vegetables are less likely to contribute to obesity or overweight. And, because they contain higher amounts of dietary fiber and other nutrients, they are associated with a lower risk for diabetes and insulin resistance. For the same reasons, they also make people feel full with fewer calories, further helping to prevent weight gain.Lifestyle CausesYou might be surprised by how many daily lifestyle habits can contribute, over time, to the development of obesity. Of particular concern is the increasingly sedentary lifestyle that more and more people around the world have adopted.From driving to work each day to sitting at a desk for hours on end—and then, for many, going home and sitting in front of the television—many of us remain sedentary for too long on a daily basis, and this has been linked to weight gain and obesity.In fact, not only is a sedentary lifestyle associated with a greater risk for obesity, cancer, and cardiovascular disease, but research has shown that sitting still for as little as 30 minutes can have detrimental effects throughout the body.In a study that examined heart scans and physical activity records of more than 2,000 adults living in Dallas, researchers found that each hour spent in a purely sedentary state per day was associated with a 14 percent increase in coronary artery calcification (calcium in the coronary arteries, which is a marker of atherosclerosis, also known as “hardening of the arteries” or arterial plaque).Another cause of obesity that appears to be linked to the modern lifestyle is sleep deprivation. Most studies have shown that seven to nine hours of uninterrupted sleep per night are required to reap the health benefits of good sleep, including those related to preventing obesity.Other studies have shown that going to bed too late can result in weight gain, especially for teenagers and young adults.Yet another consequence of the modern lifestyle that can lead to weight gain and obesity is chronic stress. There are many ways in which chronic stress has been linked to overweight and obesity. If you’ve ever given in to emotional eating or the craving for “comfort food,” you know firsthand how stress can affect the way you eat.Additionally, being under chronic stress causes the body to activate biological pathways involving stress-related factors and stress hormones such as cortisol, which also cause the body to hold on to extra weight more easily.Some of the healthiest ways to beat stress also turn out to be ways to become less sedentary and to fight obesity in general. These include taking regular walks, developing an exercise routine, spending time with your pet, and taking the time to prepare and enjoy a home-cooked meal.Medical CausesThere are some medical disorders that can be associated with overweight and obesity. Some such conditions include hypothyroidism, polycystic ovary syndrome, and Cushing syndrome, to name a few.Some medications, such as certain antidepressants, are notoriously linked to weight gain.If you believe you may be gaining weight due to a medical condition or have noticed weight gain after starting a medication, be sure to discuss your concern with your doctor. These are causes of obesity that can be treated and usually reversed, but medical intervention is required to do so.Genetic LinksBiological links to obesity, including particular gene mutations, are continually being researched and uncovered. For example, scientists have now discovered a gene, known as the FTO gene, that may confer a tendency toward binge eating and development of obesity in adolescents.The FTO gene also appears to be associated with effects on appetite, food intake, and body mass index (BMI). Based on study results, researchers now believe that there may be a relationship between FTO, binge eating, and obesity.In a study of nearly 1,000 patients in South Africa, scientists found four genetic markers (one of which involved the FTO gene) that were associated with higher BMI at the age of 13.Another study looking at the effects of FTO in over 3,000 Chinese children found that the effects of FTO on higher BMI also led to an associated risk of high blood pressure (hypertension), which is known to be caused by obesity.Uncovering such links may be important to new treatments for obesity. It is even possible that gene therapy could one day be used to treat obesity.A Word From VerywellThere are many known causes of obesity. If you recognize that any of the above apply to you or a loved one, resolve to take action to address the cause, keeping in mind that even small adjustments to your lifestyle and diet on a daily basis can add up over the long term. The bigger picture of your long-term health is worth a few small changes to your daily routine.Sources:Lombard Z, Crowther NJ, van der Merwe L, et al. Appetite regulation genes are associated with body mass index in black South African adolescents: a genetic association study. BMJ Open. 2012;2(3).Shikany JM, Safford MM, Newby PK, et al. Southern dietary pattern is associated with hazard of acute coronary heart disease in the reasons for geographic and racial differences in stroke (REGARDS) study. Circulation. 2015 Aug 10. [Epub ahead of print]Thosar SS, Bielko SL, Mather KJ, et al. Effect of prolonged sitting and breaks in sitting time on endothelial function. Med Sci Sports Exerc. 2014 Aug 18. [Epub ahead of print]World Health Organization. Information sheet: promoting fruit and vegetable consumption around the world. Updated 2016.Xi B, Zhao X, Shen Y, et al. Associations of obesity susceptibility loci with hypertension in Chinese children. Int J Obes (Lond). 2013;37:926-30.