Weight gain is an increase in body weight which can occur due to increase in muscle mass, fatty acids accumulation or even buildup of excess water.
Weight gain has been linked to many health conditions like obesity, diabetes, heart disease, and hypothyroidism.
According to the WHO, world wide obesity has tripled since 1975, and around 39% of the adults in the world are overweight.
A person is considered overweight if the Body Mass Index (BMI) is greater than 25.
Reasons for Weight Gain
There are two globally seen reasons for weight gain:
1. You consume more energy (calories) than you expend
2. A sedentary lifestyle with very little to no physical activities
Other leading causes for weight regain include:
Food Addiction
Foods that are sugar and fat-filled tend to stimulate the reward center in your brain (regions in the brain that give rise to feelings of pleasure and reward). Prolonged junk food consumption can thus cause addiction. Food addiction is often compared with addiction to alcohol and drugs.
Insulin Resistance
Insulin regulates blood sugar levels by moving the sugar into cells. It also promotes fat storage in the body. Insulin resistance leads to increased production of insulin. This leads to increased hunger and appetite.
Leptin Resistance
Leptin is a satiety hormone that reduces appetite. With leptin resistance, the hormone fails to signal to the brain how high the fat storage is in your body. This is one of the main causes of obesity in adults.
Aging
Muscles are an efficient calorie burner. As you age, your muscle mass decreases, and as a result, you tend to burn fewer calories. If the diet is not adjusted accordingly, it may result in weight gain.
Steroids treatment
Steroids are usually used to treat conditions like arthritis and asthma. Steroids affect your metabolism and the way your body stores fats. It also increases your appetite leading to weight gain, especially in the abdominal area.
Stress
Different people respond in different ways to stress - while for some people, stress may result in weight loss, in most others, it leads to weight gain. When the stress hormone cortisol levels increase, your appetite also increases, which can lead to overeating and weight gain.
Evolutionary Concept Of Fat Storage and Weight Gain
In the evolutionary history of humankind, body fat seems to have been nature’s way of storing its own food reserves. During the times of famine, people who had these “thrifty” genes that could store the greatest amount of food as fat had a better survival advantage than the others. In fact, this ability to produce more fat from less food intake may have been the difference between life and death for the species.
Fast-forwarding to this era of surplus food availability, these genes are no longer “advantageous.” In fact, it is those very same genes that have been implicated in obesity and weight gain. The easy availability of high-calorie foods and reduced physical activities seem to be the two main players that account for obesity.
How Does Genetics Contribute to Weight Gain?
More than 400 genes have been studied in association with overweight and obesity - however, only a few of them have shown a strong influence on weight gain. These genes play a role in:
- How your body stores and burns off the fat
- Your appetite
- The levels of hunger and satiety hormones
- How your body responds to stress.
The influence that genes exert over all these variables differ from person to person. Knowing the extent to which your genes influence weight gain can come in handy for weight management and weight loss measures.
FTO Gene and Tendency to Gain Weight
FTO gene is located in chromosome 16 and encodes the enzyme alpha-ketoglutarate dependent dioxygenase FTO. FTO gene is highly active in the hypothalamus region of your brain, which controls appetite. This was the first gene to be linked to obesity. Even though the association was observed only in Europeans at first, many studies since then have confirmed the same effect on other populations. Even now, many scientists suggest that the FTO gene has the largest known effect on body weight.
rs9939609 of FTO Gene and Tendency to Gain Weight
rs9939609 is a well-researched SNP in the FTO gene. The A allele in this gene is associated with an increased expression of the FTO gene. People with the AA and AG types have an increased appetite and tend to gain more weight than those with the GG type.
Several other genes, like BDNF, LEP, ADIPOQ, ADRB1, UCP, PCSK, etc., also influence your tendency to gain weight.
Medical Conditions That Cause Weight Gain
Underactive Thyroid
An underactive thyroid leads to a decreased production of thyroid hormones - a condition known as hypothyroidism. This results in slowed-down metabolism, which may contribute to weight gain.
Cushing Syndrome
Cushing syndrome is a condition characterized by increased production of the cortisol hormone. Elevated levels of cortisol interfere with your metabolism and may put you at risk for weight gain. It also results in deposits of fatty tissues at the midsection, face, and lower back.
Insomnia
Insomnia is another condition that results in elevated levels of cortisol as well as another hormone, insulin. These hormones can interfere with the secretion of hunger and satiety hormones, making you crave sugary and fatty foods.
Polycystic Ovarian Syndrome (PCOS)
This condition is commonly observed in women of early reproductive ages. PCOS occurs due to a buildup of the male hormone, androgen. Elevated androgen levels lead to insensitivity to insulin. As a result, blood sugar builds up, leading to weight gain.
Congestive Heart Failure
Congestive heart failure occurs when your heart cannot pump out enough blood to meet your body’s needs. As a result, blood and other fluids can build up in your ankles and feet, resulting in swelling and rapid weight gain.
Recommendations to Avoid Weight Gain
Maintain Your Calorie Intake
Your calorie requirement is based on your gender, body weight, age, and level of physical activity. After you calculate your calorie needs, estimate your calorie intake, and match them to your needs. If you are looking to lose weight, consume fewer calories.
Cut Back On Added Sugar
Cane sugar is essentially sucrose, which is harmful to the body when consumed in higher quantities. This type of sugar is often added to sweets and foods and can cause weight gain.
Build Your Muscle Mass
Muscle building powers up your metabolism and minimizes naturally occurring muscle loss. This way, if you choose your calories wisely, you can consume more of them without the threat of gaining weight.
Manage Your Stress Levels
Stress, as we know by now, leads to weight gain. People who are stressed out tend to overeat and go for high-calorie comfort foods. Stress can be identified with some warning signs like irritability, anxiety, and muscle tension. Meditation, a healthy sleep cycle, yoga, and mindful eating are excellent ways to combat unwanted stress.
Summary
- The two major contributors to weight gain seen globally are reduced physical activity and excess consumption of high-calorie foods. Other factors like aging, stress, and medical conditions like hypothyroidism and insomnia can also lead to weight gain.
- During prehistoric times, fat storage seemed to have provided a survival advantage to our ancestors during the times of famine. However, in this era of excess food availability, the same genes have become a liability for weight gain.
- The FTO gene, also called the fat gene, has the greatest association with weight gain. It is also associated with regulating the appetite. The A allele in the SNP rs9939609 of the FTO gene increases the gene expression, thereby the appetite. This increases your risk of weight gain.
- Some methods to control weight gain are maintaining your calorie intake, cutting back on sugar, working your muscles, getting adequate sleep, and managing your stress levels.
Reference
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2235907/
https://www.healthline.com/nutrition/leptin-101/
https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/metabolism/art-20046508/
https://www.healthline.com/health/steroids-and-weight-gain
https://www.medicinenet.com/does_stress_make_you_fat/ask.htm
https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/fto-gene
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6077364/
