Why do people get obesity? Review


This article is a thorough review on why do people get obesity. Overweight and Obesity can affect your health and life more than you think. Obesity occurs slowly in time when you eat more calories than you burn. It´s curious that while some people eat the same amount of calories, some of them gain weight and others don´t, so I would ask myself a question: Why do people get obesity?

Let´s find out some obesity facts that will help you understand why is losing weight hard and what causes weight gain and obesity.

Why do people get obesity

Genetic predisposition

Obesity prevalence has increased worldwide. There are so many unsuccessful dieting stories, it makes you think that there has to be more explanations to obesity than just overeating and under exercising. Many factors influence the appearance of obesity over time, starting with genetic inheritance.

There is a genetic predisposition to obesity and it affects a person´s life in many ways, some of them are sense of fullness, appetite, metabolism and body fat distribution. People that have a stronger genetic influence to get obesity have been overweight most of their lives, they can´t lose weight even when they stick to the diet and exercise programs, and both of their parents or relatives usually are overweight too.

Why do people get obesity

Slow metabolism

Metabolism is also determined by heredity. It is the process by which the body converts the nutrients into energy. The basal metabolic rate (BMR) is the amount of energy burned at rest over time. Around 75 percent of our total energy is expended at rest to maintain vital functions such as body temperature, breathing, digestion, circulation, and glandular activity.

One person’s metabolic rate may be faster or slower than someone else’s, so two persons can go walking together and eat the same number of calories, but the one with the lower BMR is going to burn fewer calories. When more calories are taken in than are expended, they get stored in the form of body fat.

Endocrine abnormalities

Insulin resistance.

The hormone insulin binds to tissue cells and allows them to absorb blood sugar (glucose). In people who are insulin resistant, the cells can´t absorb sugar effectively. The sugar builds up in the body, instead of being used for energy. Insulin resistance can lead to type 2 diabetes.


People with hypothyroidism have low levels of thyroid hormones. Therefore, the metabolism gets slower, and they tend to gain weight, even with not overeating. Their body temperature is lower and do not efficiently use stored fat for energy.

Cushing’s syndrome.

People with this disease have high cortisol blood levels, which make the body feel stressed. The consequence is an increase in appetite and more fat storage.

Organic factors

Organic factors explain why some people eat anything they want and never seem to become obese, meanwhile other people have to struggle all their lives to barely keep the excess weight off.

Low leptin levels.

Leptin is produced by the fat cells. It signals the brain when the body feels satisfied. Low leptin levels cause overeating and reduce energy use. Some people that are very obese have extremely low concentrations of leptin. Low leptin levels may cause severe obesity and make it really hard to lose any weight.


There are two types of serotonin: one is found in the brain and regulates sleep, mood and appetite. Low levels are associated with insomnia, depression and weight gain. When central serotonin levels are down, we tend to crave more sweets, which can also lead to obesity.

The other type is found in the bloodstream, and it´s 95% of the total serotonin in the body. High levels of peripheral serotonin inhibit the brown fat that burns energy and glucose to make heat, which leads to obesity.

Lack of sleep

Sleep deprivation is associated with overweight and obesity. People who are trying to lose weight and who sleep less, usually eat more calories and snack more, which makes it harder to lose weight. Workers who pull overnight shifts may be predisposed to gain weight.

Lack of sleep affects our hormone equilibrium because it produces a decrease in leptin (losing the sense of fullness) and an increase of ghrelin (triggering hunger). The consequence is that we think we’re hungry and we eat more.

Crash diets

Crash diets don´t result in long term weight loss. On the contrary, they will lead to gaining weight over time. Skipping meals will result in tiredness, poor nutrition and the need to snack on sweet and fat foods, that will result in more weight gain.

Losing weight fast can slow your metabolism and produce a yo-yo effect leading to future weight gain. Besides, it deprives your body of essential nutrients and weakens your immune system. The healthier thing to do is to eat with moderation in a way that you can maintain over time.

Sweets and Sweetened Drinks are addictive.

Drinking a lot of sweetened beverages can cause you to gain weight. These drinks can add a lot of calories to your diet.

Sugar has been found to produce some symptoms similar to addictive substances. Such symptoms are bingeing, craving, tolerance, withdrawal, cross-sensitisation, cross-tolerance, cross-dependence, reward and opioid effects. Sugar may be addictive when consumed in a binge-like manner.

Sugar makes us obese, can promote the development of type 2 diabetes, raises our blood pressure and gives us fatty livers. But it also alters our mood, making us feel rewarded and euphoric.


Menopause is associated with weight gain, especially central fat distribution, due to a decrease in estrogen. Appetite also increases in perimenopause due to an increase in the hunger hormone ghrelin, which will lead to eat more.

The low estrogen in menopause also impair the function of leptine and neuropeptide Y, which are hormones that control fullness and appetite, leading to eating more and storing more fat.

Therefore, it´s important that at midlife, women start reducing the amount of calorie intake and practice more physical activity.

Poor physical activity

We can´t change our genes predisposition to gaining weight, but we do can change how much physical activity we get every day. Obesity is associated with sedentarism or poor physical activity.

If we want to stay healthy, we should do at least 150 minutes of moderate exercise each week, that´s what the American Heart Association (AHA) recommends for reducing the risk of cardiovascular disease and stroke. However, if we want to lose weight, that is not enough, in that case, we should do at least 1 hour every day of moderate to vigorous physical activity (the AHA recommends 200-300 minutes per week).

Moderate physical activity might be a brisk walk, bicycling or jogging. While vigorous physical activity would be running or high impact aerobics. Also, it is recommendable to do some weights and strength exercises to build up bone and muscle, because the muscle burns more energy at rest than the fat cells.

Unhealthy eating habits

Bad eating behaviors are modifiable factors for the development of obesity. We should aim to change those bad habits like: eating in front of the TV, eating out fast food, skipping breakfast or meals, snaking on sweets and junk food, drinking too much sweet beverages or emotional eating.

Replace unhealthy habits with new healthy ones, and focus on the good changes not on what you are missing, but on what you are adding. For example, focus on always filling half of your plate with vegetables and fruits, always having some fruit, dried fruit or seeds for snacks, never leave home without eating breakfast, eat slowly at the table enjoying every bite you put into your mouth. When you feel anxious, go out and take a nice walk. Resist cravings for sweets, after 20 minutes, they will go away, do something that keeps you busy or distracted until de cravings pass.

My final opinion

There are many reasons why people get obesity, and it is more complex than just not getting enough exercise and not eating right. However, to succeed in achieving a healthy weight is necessary to understand how our bodies work and why sometimes it´s so difficult to loose weight or maintain the weight we have lost.

Maybe you are struggling with losing weight at this moment in your life, if you would like to know how is the fastest way to lose weight and keep it off forever, read my article clicking here.

I recommend you to focus more on living a healthier lifestyle than on losing weight. If you would like to know more about what is a healthy lifestyle, read my article clicking here.

If you would like to lose weight following an effective and healthy proven system, read my review of The Mayo Clinic Diet, just click here.

If you have any questions, don´t hesitate to leave your comments bellow and I´ll do my best to help you out.

Your friend,

Dr. Verónica

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