Causes of Obesity & How You Can Address Them

The causes of obesity are numerous and diverse. Rather than simply listing them, let’s explore them based on which ones you can control and which you can’t…

Factors Directly Under Your Control
Calories, Sleep, Sedentary Lifestyles and Food Addiction

Calories Consumed Minus Calories Burned

When obesity causes can be impacted by your daily decisions and actions, they can be said to be under your “direct control.” In other words, direct causes of obesity are typically the result of your chosen lifestyle.

Many “experts” often attempt to cram the direct obesity factors into one neat and tidy formula:

Weight Gain/Loss = Calories ConsumedCalories Burned

From this viewpoint, in order to lose weight all you need to do is exercise (burn) off more calories than you eat. But things are a little more complicated than that…

Sedentary Lifestyles

A sedentary lifestyle means living with minimal (or zero) physical activity. The dangers of a sedentary lifestyle include developing obesity and other health problems (1). Unfortunately, this dangerous lifestyle is becoming more common as obesity rates rise (2).

Trends toward a sedentary lifestyle and obesity appear to be starting at a young age childhood Engagement in physical activity is decreasing, contributing to the rising obesity rates (3). Additionally, the amount of time children spend watching television is proportional to the risk of developing obesity (4).

In adults, various factors contribute to the rise in sedentary lifestyles. These include ease of transportation, jobs without physical activity, and technology (5).


Another factor that can lead to obesity is poor sleep hygiene (6). A lack of sleep stresses the body, disrupts hormone regulation, and interferes with sugar processing. As a result, obesity risk is increased for people who sleep less than six hours a night (7).

Food Addiction

Food addiction is compulsive eating despite negative consequences. Dopamine plays a significant role in addiction, and studies have confirmed a relationship between dopamine and food (8). Most unhealthy, desirable foods (think pizza and candy) release more dopamine in our brains than healthy foods (think vegetables and beans) (9).

Screening for food addiction is sometimes the first step in obesity treatment. If food addiction is present, there may be additional treatment recommendations that includes psychotherapy . Psychotherapy will address emotional issues that contribute to compulsive eating.

For more information, see our page Food Addiction Treatment: Symptoms, Diagnosis, & Potential “Cures”

Calories Consumed: Diet-Related Causes of Obesity

From the diet, or “calories consumed”, standpoint, the confluence of 3 factors can lead to obesity:

1. Where your calories come from

According to Merriam-Webster, a calorie is the amount of heat (energy) required to raise the temperature of one gram of water one degree Celsius. But this definition does not go far enough.

How Full Will You Feel?

Using the results from numerous satiety studies, NutritionData created a complex formula that determines the “Fullness Factor” (the higher the rating, the fuller you feel per calorie consumed) of a variety of common foods based on their nutritional content:

  • 4.6 Bean Sprouts
  • 4.5 Watermelon
  • 4.0 Grapefruit
  • 3.8 Carrots
  • 3.5 Oranges
  • 3.4 Fish, broiled
  • 3.3 Chicken breast, roasted
  • 3.3 Apples
  • 3.2 Sirloin steak, broiled
  • 3.0 Oatmeal
  • 2.9 Popcorn
  • 2.5 Baked potato
  • 2.5 Lowfat yogurt
  • 2.5 Banana
  • 2.5 Macaroni and cheese
  • 2.3 Brown rice
  • 2.2 Spaghetti
  • 2.1 Pizza
  • 2.1 White rice
  • 2.0 Peanuts
  • 1.8 Ice cream
  • 1.8 White bread
  • 1.6 Raisins
  • 1.5 Snickers Bar
  • 1.4 Honey
  • 1.3 Sugar (sucrose)
  • 1.3 Glucose
  • 1.2 Potato chips
  • 0.5 Butter

If a calorie were a calorie regardless of its source, we could just load up on ice cream and french fries every meal as long as we exercised enough to burn them off. Common sense tells us this is ridiculous, but why?

In short, all calories are not created equal. Both your body and mind respond to different foods in different ways (10)…

  • How easily is the food broken down by your body?

    Fibrous foods like fruits and vegetables are more difficult for your body to digest and therefore require more energy (burned calories) to break down. In addition, fibrous foods cannot be entirely broken down by your digestive system, so not all fibrous food calories are absorbed.

    In contrast, calories from foods high in fat and carbohydrates are much more easily broken down by your body. As a result, your body burns fewer calories while absorbing them, and their calories are almost entirely absorbed.

    To compound the issue, when your body works harder to burn calories, your body’s overall metabolism (the rate at which your body burns calories) goes up. This causes your body to burn calories more efficiently in the future which leads to more calories burned.

    • Takeaway: Eat fibrous foods like fruits and vegetables.
  • How full does the food make you feel?

    Foods high in protein are the most filling, while foods high in fat are the least filling. So when you eat fatty foots, it takes you longer to feel full which will most likely cause you to consumer more calories.

    The exception? Nuts are high in both protein and fat, and several studies (11) have shown that they both increase satiety (make you feel full) and increase metabolism.

    • Takeaway: Along with fibrous foods, include a portion of protein with your meals to feel full sooner. Consider adding nuts (in their raw or healthily cooked forms) to your salad or as a side dish.

The importance of water

Making up about 60% of your body’s weight, water is the most important substance you consume. So how much do you need to drink?

According to the Institute of Medicine, men should consume just over 15 1/2 cups (3.7 liters) of total beverages per day while women should consume about 11 1/2 cups (2.7 liters).

  • Solids or liquids?

    Solid foods cause your body to feel full sooner, while liquids, even healthy ones like juices and milk, leave your body feeling hungry. The result: fluids may add to your overall caloric intake.

    This could explain some of the obesity epidemic in the U.S. Even though soda consumption is on the decline in the U.S., Americans still drink the second most amount of soda per person, coming just short of Argentina in 2015 (12).
    • Takeaway: When there’s a choice, choose solids over liquids (i.e. eat an apple instead of drinking apple juice). Note: Recommended levels of water intake should be maintained (see sidebar).
  • Low-carb or low-fat?

    According to a recent study published in the Annals of Internal Medicine (13), obese individuals on a low-fat diet continue to lose weight three years after going on a diet, while those on a low-carbohydrate diet tend to gain all of their weight back.

    How Sugar is Listed on Food Labels

    • Agave nectar
    • Brown sugar
    • Cane crystals
    • Cane sugar
    • Corn sweetener
    • Corn syrup
    • Crystalline fructose
    • Dextrose
    • Evaporated cane juice
    • Fructose
    • Fruit juice concentrates
    • Glucose
    • High-fructose corn syrup
    • Honey
    • Invert sugar
    • Lactose
    • Maltose
    • Malt syrup
    • Molasses
    • Raw sugar
    • Sucrose
    • Sugar
    • Syrup
    Quicker weight loss from dieting is typically followed by quicker weight regain, while diets leading to slower weight loss are easier to maintain. In addition, there are no “off-limits” food groups in a lower-fat diet, only minor changes to an existing diet. These minor changes are often more sustainable for obese individuals, resulting in a better chance for continued weight loss.

    Another important consideration is where your carbohydrates come from. Evidence is (re)emerging that suggests sugar could be the true cause of the obesity epidemic and many of the obesity-related health problems. Unless your sugars are coming from natural sources such as fruit (which has a much higher percentage of health ingredients such as fiber, vitamins and micronutrients) do your best to keep them out of your diet.

    • Takeaway: If you’re choosing between cutting carbs or fat, cut fat. It may take you longer to lose, but you will be more likely to keep the weight off over the long-term and to continue losing weight.

      When choosing your carbs, stay away from processed sugars (see the box to the right for several ways that processed sugar is listed on food labels – the higher up these terms are on the ingredient list, the more sugar the product has).
  • Home cooked or Takeout?

    According to the Economic Research Service (ERS) (14), for the first time since tracking the data, Americans spent more money on food outside the home than they did on food at home.

    This is important for two reasons:

    1. Portions away from the home are often larger. For example, according to the CDC, portion sizes at fast food restaurants have increased by 400% since the 1950s (15).
    2. Food away from home typically contains more calories. For example, it is estimated by the ERS that just 1 meal away from home per week could increase the weight of an average person by 2 pounds per year (16).

    If you’re looking for some healthy eating tips, especially if you have already had weight loss surgery, check out our Bariatric Diet page.

    • Takeaway: When choosing between cooking at home or ordering out, choose to cook at home whenever possible. It will save you money, it can be a great time for bringing the family together, and it is MUCH healthier than ordering out.

2. How much food you eat per meal

Research has proven that we tend to eat all of the food that is placed in front of us, regardless of whether we feel full (17). To control your calories consumed, you must control your portion sizes when eating at home and in restaurants.

  • Takeaway: Know the amount of calories that you are consuming per meal. We recommend planning your meals through the use of a good free diet journal.

Recommended Reading

For a great read that further explores what you should eat and why, pick up the book In Defense of Food: An Eater’s Manifesto by Michael Pollan.

It will change the way you think about food and, hopefully, the decisions you make when buying it.

Our Fast Food Obesity page provides additional analysis of how food content and portion sizes can lead to obesity, but there’s another more snacky…um…sneaky cause of obesity lurking around every corner…

3. How often you eat

How many meals do you eat per day? Breakfast, lunch and dinner make three, right?

Not so fast.

When snacking between meals is factored in, the average adult eats the equivalent of four meals per day while the average child eats almost five (18).

The amount of carbohydrates and fats in the average American diet has increased dramatically over the last 40 years, and food and beverage snacks account for almost all of it; Americans today get almost a quarter of all calories from snacking (19).

  • Takeaway: Don’t snack. If you do, make sure your snacks are planned and consist of a healthy alternative.

That takes care of the “calories consumed” part of the weight loss/weight gain formula. Now let’s explore the causes of obesity related to calories burned…

Calories Burned: Exercise-Related Causes of Obesity

According to the Centers for Disease Control and Prevention, most adults need at least 30 minutes of moderate physical activity at least five days per week. Moderate physical activity includes anything that increases your breathing or heart rate such as walking briskly, bicycling, dancing, swimming or mowing the lawn.

Work-Life Balance

According to recent research of data spanning more than 50 years, another big cause of our rising obesity rates is the drastic reduction of physically-demanding jobs. In 1960, 50% of all jobs in the U.S. required "moderate physical activity. That percentage has now dropped to about 20%.

Currently, over two-thirds of Americans are not achieving this (20).

In addition to burning calories directly, exercise further prevents obesity by increasing metabolism (the rate at which your body burns calories). Just as importantly, exercise reduces abdominal obesity, which is a big predictor of obesity health problems.

  • Takeaway: Exercise moderately for at least 5 days per week, 30 minutes per day.

Contradicting Evidence

Recent research suggests that your metabolic rate may not be as important as previously thought, especially when compared to an improved diet.

Regardless, good weight loss results and better overall health speak for themselves… a healthy diet combined with an appropriate exercise program equals long-term success.

When addressing the causes of obesity, many weight loss professionals, web sites and publications primarily focus on calories consumed versus calories burned. As we’ve discussed, these are certainly big contributors, but there is more to the problem…

Sugar may be the primary culprit

Consider the following:

  • According to the World Health Organization, “A high level of [sugar] intake is of concern, because of its association with poor dietary quality, obesity and risk of noncommunicable diseases” (e.g. diabetes, cardiac problems, etc). “There is increasing concern that intake of [sugar] – particularly in the form of sugar-sweetened beverages – increases overall energy intake and may reduce the intake of foods containing more nutritionally adequate calories, leading to an unhealthy diet, weight gain and increased risk of” noncommunicable diseases (e.g. diabetes, cardiac problems, etc) (21).
  • Diets high in sugar are associated with heart problems (22).
  • Sugar-sweetened beverages increase the risk of Type 2 Diabetes (23).
  • Added sugar is tough to identify because it has so many names, such as brown rice syrup, sucrose, treacle, honey, gomme, clintose, sorghum, versatose, and many others.

Why do so many people believe that diets high in fat are bad? How has sugar stayed “off of the radar” for so long as a potential cause of obesity?

According to a peer-reviewed publication in the Journal of the American Medical Association, “together with other recent analyses of sugar industry documents, our findings suggest the industry sponsored a research program in the 1960s and 1970s that successfully cast doubt about the hazards of sucrose while promoting fat as the dietary culprit in coronary heart disease (CHD). Policymaking committees should consider giving less weight to food industry–funded studies and include mechanistic and animal studies as well as studies appraising the effect of added sugars on multiple CHD biomarkers and disease development (24).”

In other words, the sugar lobby may have had an impact on the government’s representation of sugar as part of the problem.

As a result of the mounting evidence against sugar, as of 2018, the FDA requires all labels to include the amount of added sugar in each product and it’s percent daily value (labels prior to 2018 were not required to include either of these.

Factors Indirectly Under Your Control
Genetics And Government Interventions

Factors Indirectly Under Your Control: Genetics And Government Interventions

While a healthy diet and adequate exercise may be difficult to achieve due to our stressful and time-strained lifestyles, they remain under our day-to-day control nonetheless.

Two additional causes of obesity are also under our control, but impacting them requires much more work and dedication…

1. Genetic Causes of Obesity

Combined with environmental influences (i.e. diet and exercise), your genes are up to 70% responsible for your body’s weight.

Not only do your genes determine how hungry you feel and your metabolism, but they are also responsible for how heavy your body “wants” to be (also called the Set Point Theory).

But how can your genetics be under your control, even indirectly?

While you cannot change your actual genes, there are a couple of ways that you may be able to work around them.

First, talk with your doctor about whether medication could be an option. If it is, the most effective diet pill for you will most likely fall into one of two categories:

  1. Appetite suppressants (sibutramine, phentermine, diethylpropion and phendimetrazine) make you feel full or lower your appetite.
  2. Lipase inhibitors (orlistat) reduce the body’s ability to absorb fat.

Weight loss surgery is another effective way to alter your body processes, thereby circumventing any obesity predisposition from your genes. However, there are very specific requirements in order to qualify. If you do qualify, surgery is a life-changing decision that should be taken very seriously and carefully considered.

See our Obesity and Genetics and Bariatric Treatment pages for all of the details.

  • Takeaway: Prescription diet pills and bariatric treatment are not for everyone, but if you are morbidly obese and your weight loss attempts have repeatedly failed, they may be an option.

2. Government Influence on the Causes of Obesity

The government recognizes that they can impact the causes of obesity, but critics of government intervention point out the dangers in attempting to usher people towards a healthier lifestyle.

“Obesity laws” that have been considered to date include…

  • Obesity tax on junk food
  • Tax-free gym memberships
  • Tax deductions for bicycle commuters
  • Junk food ban from public institutions and schools
  • Prohibition of brand-name fast foods from being offered in public schools
  • Requirement of fruits or vegetables to be offered at public institutions and schools when other food options are available
  • Mandates of weight loss surgery insurance or Medicaid offerings

Success in implementing laws like these has been extremely limited, and where success has been achieved, it has rarely gone as far as intended.

For example, junk food has been banned from public school breakfasts and lunches, but little has been done to curb the junk food that is easily available outside of these “official” meals. In addition to junk food and soft drinks filling most on-campus vending machines, many schools have branded fast food available on campus (11.7% of elementary schools, 19% of middle schools and 23.5% of high schools (25).

For those schools without on-campus fast food, chances are there are many options very nearby… fast food companies make a point of it. And children that have a fast food restaurant within 0.10 miles of their school have a 5.2% greater chance of being obese.

Here is what Ray Kroc, founder of McDonald’s Corporation, had to say about opening restaurants close to schools (26)…

“Back in the day when we first got a company airplane, we used to spot good locations for McDonalds stores by flying over a community and looking for schools. Now we use a helicopter, and its ideal.”

Ray Kroc, McDonalds Corp. Founder

Despite the apparent necessity of government involvement in areas like junk food at and around schools, other areas are not so clear-cut. For instance, a big reason that fast food is so popular is its low cost. It gives low-income individuals, people who may otherwise not be able to afford to feed their families, an inexpensive option to eat. While government taxation on fast food may encourage the purchase of healthier alternatives for those who can afford it, it may make three meals per day unaffordable for low-income families.

From a less humanistic point of view, critics of government intervention point out that obesity taxes unfairly impose on your freedom of choice. In other words, if you want a burger, what gives the government the right to make you pay more for it while they pocket the difference?

Critics also site the fundamentals of capitalism and the importance of allowing the free market to decide what it wants. After all, the increase in popularity of organic products, even with their higher cost, shows that the market is capable of making healthy decisions.

But proponents of obesity legislation draw upon the cigarette tax analogy: just like cigarettes, obesity results in a much larger overarching public health concern that negatively affects the lives of everyone (i.e. increasing healthcare costs) and should therefore be addressed with public policy.

It has also been suggested that government involvement can take us in the opposite direction. For example, the creators of the documentary Food, Inc. suggest that government food industry subsidies make unhealthy food cheaper, thereby encouraging more of the population to consume unhealthy food.

causes of obesityAnother example is the government-published Choose My Plate Initiative.

At a minimum, the Choose My Plate Initiative is far too general. At a maximum, the recommendations of the Choose My Plate Initiative significantly contribute to public misperceptions about what to eat.

For instance, as explored further up the page, all calories from carbohydrates are not created equal and should not be lumped together into one group. In addition to its problem with generalization of food groups, nuts are not featured despite their positive health effects.

Critics of the Choose My Plate Initiative also question the organization who is responsible for it: the United States Department of Agriculture (USDA). The USDA is responsible for promoting and regulating agriculture, not for overseeing the health of America. These critics feel that agencies directly responsible for health issues such as the National Institutes of Health (NIH) or the Department of Health and Human Services are much more qualified to create unbiased recommendations.

Government’s recognition of their potential impact on the causes of obesity continues to increase, and a good supporting argument for it exists in at least some areas. The difficulty comes with walking the tight rope between encouraging positive behavior change and hindering individual freedom of choice. Regardless of the level of government involvement, care must be taken and changes must be made in order to keep the fight against obesity moving in the right direction.

  • Takeaway: Help drive the obesity legislation that you feel is appropriate by voting and by writing to your political representatives. Here are links by country for more information about each:
United Kingdom
United Kingdom
United States
United States
Voting Links
United Kingdom
United States

3. Falling Nutritional Value of Food

Other factors indirectly under your control are the relative nutritional value of your food and its availability.

First, food just isn’t as healthy as it used to be. For example, from 1977 to 2010 there was a 30% increase in the amount of added sugars in foods that Americans eat.

In terms of calories, Americans went from eating 277 calories worth of sugar per day to 329 calories of sugar per day. The problem with having more sugar in foods is that it’s energy-dense and nutrient-poor. In other words, we’re trading healthy calories for unhealthy ones.

The other problem is the availability of healthy food. A study published in 2010 in the American Journal of Preventive Medicine found that the available amount of “dark-green/orange vegetables and legumes and whole grains were entirely insufficient relative to recommendations, with virtually no change over time” (27). In other words, there’s not enough healthy food to go around.

Factors That Are Out Of Your Control
Obesity Virus, Certain Types Of Intenstinal Bacteria

Factors That Are Out Of Your Control: Obesity Virus, Certain Types Of Intenstinal Bacteria

Unfortunately, some factors of obesity are just out of your control. Here are some examples:

Food Advertising

Advertising can have a big impact on our behaviors, which is why food companies spend so much money on advertising. This would be fine if they were advertising healthy food, but unfortunately, this advertising goes in large part to unhealthy food.

Also, that spending is going up – from 2010 to 2014, a study by the Rudd Center for Food Policy and Obesity found a large spending increase in ads targeting children and teens. For example, they found:

  • A 32% increase in TV ads for children for savory snacks
  • A 17% increase for sweet snack TV ads directed at teens
  • A 62% increase in savory snack ads viewed by teens
  • PepsiCO doubled their advertising targeting children and tripled their advertising targeting teens

In addition to TV advertising, there is a significant amount of internet advertising directed at older children and teens. From 2010 to 2014 snack food companies placed 163 million ads on Facebook and Youtube, a month. This content also often gets shared by teens, amplifying the reach of these ads.

Obesity Virus

The obesity virus increases the amount that your fat cells can hold and speeds up the rate at which they mature. Although it can be “caught” from other people, not everyone who has it is obese or even overweight. One study found that about 30% of obese people and 11% of lean people have the virus in their system.

Intestinal Bacteria

Research has also shown that some obese people carry different types of intestinal bacteria than lean people (28). According to Dr. Andrew Gewirtz, PhD of Emory University, “intestinal bacteria contribute to changes in appetite and metabolism.”

The current scientific consensus is that the bacteria each of us has in our intestines was inherited from our parents. However, Dr. Gewirtz’s research found that intestinal bacteria causing increased appetite in mice can be transferred from mouse to mouse, suggesting the same may hold true for humans. His team is planning future research in humans to determine whether this is the case.

Unfortunately, if you have the obesity virus or hunger-inducing intestinal bacteria, there is currently no treatment to get rid of them. Also, with so many screens in today’s world, it’s almost impossible to avoid advertising of some kind. The good news is that even if you are affected by them, they play only a small role in your overall weight when compared to the causes of obesity that are under your control.

  • Takeaway: Don’t sweat the small stuff. The factors under your control have a far greater impact on your weight.

Top 5 Ways To Combat The Causes Of Obesity

Summary: Top 5 Ways To Combat The Causes Of Obesity

As we’ve discussed, there are several causes of obesity, most of which are either directly or indirectly under your control. Depending on your situation, consider adopting one or more of the following approaches…

  • Adhere to the following diet recommendations:
    • Eat fibrous foods like fruits and vegetables.
    • Include a portion of protein with your meals to feel full sooner. Consider adding nuts (in their raw or healthily cooked forms) to your salad or as a side dish.
    • When there’s a choice, choose solids over liquids (but keep the water intake high).
    • If you’re choosing between cutting carbohydrates or fat, cut fat. It may take you longer to lose, but you will be more likely to keep the weight off over the long-term and continue losing weight with a low-fat diet.
    • Know the amount of calories that you are consuming per meal. Consider planning your meals with a good free online diet journal.
    • Don’t snack. If you do, make sure your snacks are planned and consist of a healthy alternative.
  • Exercise moderately at least 5 days per week, 30 minutes per day.
  • Talk with your doctor about whether a prescription weight loss medication is appropriate.
  • Weight loss surgery is not for everyone, but if you are genetically predisposed to morbid obesity and your weight loss attempts have repeatedly failed.

    Click here to learn whether bariatric treatment could be an option for you.
  • Help drive the obesity legislation that you feel is appropriate by voting and by writing to your political representatives.

References for Causes of Obesity

  1. Hollis JH, Mattes RD. Are all calories created equal? Emerging issues in weight management. Current Diabetes Reports. Volume 5, Number 5 / September, 2005 pgs 374-378.
  2. Kirkmeyer SV, Mattes RD. Effects of food attributes on hunger and food intake. Int J Obes Relat Metab Disord. 2000;24:1167–75
  3. Marion L. Vetter, et al. Long-Term Effects of Low-Carbohydrate Versus Low-Fat Diets in Obese Persons. Ann Intern Med March 2, 2010 152:334-335.
  4. Ello-Martin JA, Ledikwe JH, Rolls BJ. The influence of food portion size and energy density on energy intake: implications for weight management. Am J Clin Nutr. 2005 Jul;82(1 Suppl):236S-241S.
  5. Spake, A. America’s Supersize Diet Is Fattier and Sweeter-and Deadlier. U.S. News and World Report. Aug 2002.
  6. Oliver, JE. Fat Politics: The Real Story Behind America’s Obesity Epidemic. Oxford Press. 2006. Page 123 & 133.
  7. Exercise or Physcial Activity. Centers for Disease Control and Prevention. April 2009. Available at:
  8. American School Health Association, “School Health Policies and Programs Study (SHPPS)
    2006,” Journal of School Health 77:8 (October, 2007)
  9. Clowning with Kids’ Health. Corporate Acountability International. Available at:
  10. Press Release: Intestinal Bacteria Drive Obesity and Metabolic Disease in Immune-Altered Mice. Emory University. Mar 2010. Available at:

[ Last editorial review/modification of this page : 01/11/2018]

* Disclaimer: The information contained in this website is provided for general information purposes and your specific results may vary depending on a variety of circumstances. It is not intended as nor should be relied upon as medical advice. Rather, it is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her existing physician(s). Before you use any of the information provided in the site, you should seek the advice of a qualified medical, dietary, fitness or other appropriate professional. Read More