In 2016, around 30% of adults in the United States were estimated to have obesity (1).

Many people blame obesity on poor dietary choices and inactivity, but it’s not always that simple.

Other factors can have powerful effects on body weight and obesity, some of which are outside of a person’s control.

These include genetics, environmental factors, certain medical conditions, and more.

This article lists 9 compelling reasons why obesity is not just a choice.

1. Genetics and prenatal factors

Health is especially important during early life, as this affects your health later on. In fact, a lot can be determined while the fetus is still in the womb (2).

A mother’s diet and lifestyle choices matter a great deal and may influence a baby’s future behavior and body composition.

Studies show that women who gain excessive weight during pregnancy are more likely to have heavy 3-year-olds (3, 4).

Similarly, children who have parents and grandparents who have obesity are much more likely to have obesity than kids with parents and grandparents who are normal weight (5, 6).

Furthermore, the genes you inherit from your parents may determine your susceptibility to weight gain (7).

Though genetics and early life factors are not exclusively responsible for obesity, they contribute to the problem by predisposing people to weight gain.

About 40% of children with excess weight will continue to be heavy during their teenage years, and 75−80% of teenagers with obesity will maintain this condition into adulthood (8).

SUMMARY Genetics,
a mother’s weight, and family history can all increase the likelihood of
childhood and adult obesity.

2. Birth, infancy, and childhood habits

Though the reason is unknown, children born via C-section seem more prone to obesity later in life (9, 10).

This is also true for formula-fed infants, who tend to be heavier than breastfed babies (11, 12, 13).

This may be because the two groups develop different gut bacteria, which can affect fat storage (14).

It’s important to note that these factors are generally not made by choice of either the mother or baby yet seem to be linked to the child’s obesity risk.

Additionally, forming healthy dietary and exercise habits during childhood may be the most valuable prevention against obesity and lifestyle-related diseases.

If young children develop a taste for healthy foods instead of processed junk foods, it helps them maintain normal weight throughout their life.

childhood factors may affect your risk of obesity later on. These include
childbirth method, breastfeeding, and childhood dietary and exercise habits.

3. Medications or medical conditions

Many medical conditions can only be treated with pharmaceutical drugs.

Weight gain is a common side effect of many such medications, including diabetes medications, antidepressants, and antipsychotics (15, 16, 17).

These drugs may increase your appetite, reduce your metabolism, or even alter your body’s ability to burn fat, increasing your rate of fat storage.

Additionally, many common medical conditions can predispose you to weight gain. A key example is hypothyroidism.

gain is a common side effect of many medications, including diabetes drugs,
antidepressants, and antipsychotics.

4. Powerful hunger hormones

Hunger and uncontrollable eating are not just caused by greediness or lack of willpower.

Hunger is controlled by very powerful hormones and brain chemicals, involving areas of your brain that are responsible for cravings and rewards (18, 19).

These hormones function improperly in many people with obesity, which alters their eating behavior and causes a strong physiological drive to eat more.

Your brain has a reward center, which starts secreting dopamine and other feel-good chemicals when you eat.

This is the reason why most people enjoy eating. This system also ensures that you eat enough food to get all the energy and nutrients you need.

Eating junk food releases much more of these feel-good chemicals than eating unprocessed food. This yields a much more powerful reward in your brain (20, 21, 22).

Your brain may then seek more reward by causing powerful cravings for these junk foods. This can lead to a vicious cycle that resembles addiction (23, 24, 25).

is controlled by powerful hormones. These hormones often function improperly in
people with obesity, which causes a strong physiological drive to eat more,
resulting in weight gain.

5. Leptin resistance

Leptin is a very important hormone that helps regulate appetite and metabolism (26).

It’s produced by fat cells and sends a signal to the part of your brain that tells you to stop eating.

Leptin regulates the number of calories you eat and burn, as well as how much fat your body stores (27).

The more fat contained in fat cells, the more leptin they produce. People with obesity produce a lot of leptin.

However, they also tend to have a condition called leptin resistance (28).

Thus, even though your body produces a lot of leptin, your brain doesn’t see or recognize it. When your brain doesn’t receive the leptin signal, it wrongly thinks that it’s starving, even if it has more than enough body fat stored (29, 30).

This causes your brain to change physiology and behavior to regain the fat that it thinks you’re missing (31, 32, 33).

Hunger is increased, and you burn fewer calories to prevent starvation. Trying to exert willpower against the leptin-driven starvation signal is almost impossible for many people.

Leptin resistance is common in people with
obesity. Your brain doesn’t sense the leptin that is produced and thinks that
you’re starving. This causes a powerful physiological drive to eat more.

6. Poor nutrition education

In modern society, you’re confronted with endless advertisements, health statements, nutrition claims, and unhealthy foods.

Despite the importance of nutrition, children and adults are generally not taught how to eat properly.

Teaching children the importance of a healthy diet and proper nutrition has been shown to help them make better choices later in life (34, 35, 36).

Nutrition education is very important, especially when forming the dietary and lifestyle habits that you bring into adulthood.

SUMMARY Teaching
children the importance of proper nutrition is important, but nutrition
education is generally lacking in society.

7. Addictive junk food

Some foods can be downright addictive.

Food addiction involves being addicted to junk food in the same way drug addicts are addicted to drugs (37, 38).

This is more common than you may think.

In fact, up to 20% of people may live with food addiction, and this number goes up to about 25% in people with obesity or excess weight (39).

When you become addicted to something, you lose your freedom of choice. Your brain chemistry starts making decisions for you.

foods can be addictive, and up to 25% of people with obesity or excess weight
may live with food addiction.

8. The effect of gut bacteria

Your digestive system hosts an immense number of bacteria, which are known as your gut microbiota.

Many studies show that these bacteria are incredibly important for overall health.

Interestingly, people with obesity tend to have different gut bacteria than those with a normal weight (40).

The gut bacteria in individuals with obesity or excess weight may be more efficient at harvesting energy from food, increasing the total caloric value of their diet (41, 42, 43).

While understanding of the relationship between weight and gut bacteria is limited, compelling evidence suggests that these microorganisms play an important role in obesity (41, 44, 45, 46).

with obesity have different gut bacteria than people with a normal weight. This
may cause people with obesity to store more fat.

9. The environment

In some areas, buying healthy food is simply not an option.

These areas are often called food deserts and located in urban neighborhoods or rural towns without ready access to healthy, affordable food.

This is largely due to a lack of grocery stores, farmers markets, and healthy food providers within walking distance.

Those living in these regions are often poor and may not have access to a vehicle to travel far to buy groceries.

An inability to buy healthy and fresh foods limits your diet substantially and increases your risk of problems like obesity.

Other environmental factors may play a role in obesity as well, including artificial light from electric light bulbs, computers, phones, and televisions.

Even though the link between screen use and obesity has been well established, most studies chalk this up to a lack of exercise.

However, nighttime exposure to light and changes to your inner circadian rhythm may also contribute to obesity (47, 48).

Animal studies suggest that artificial light may alter the inner circadian clock, making rodents more susceptible to obesity and metabolic syndrome (49).

environmental factors can make you more susceptible to obesity, including
living in a food desert and exposure to artificial light.

The bottom line

When it comes to obesity, multiple factors are at play, many of which are beyond your control, including genetics, childhood habits, medical conditions, and hormones.

Though becoming overweight or developing obesity may not be a choice and shedding excess weight may be difficult, you can lose weight if you choose to.