Obesity can be both genetic and environmental, occurring most often when factors of each combine. While you cannot change your genes, making healthy lifestyle choices can still help you manage your weight. Understanding genetic tendencies and environmental influences is important for finding the best way to achieve and maintain a healthy weight.
A Look Into the Genetic Factors of Obesity
Genetics can account for 40-70% of the variability in body weight status. In general, genes can influence a person’s basal metabolic rate (BMR), how a person’s body stores fat, signals fullness and metabolizes nutrients, and how their body responds to diet and exercise.
The primary genetic factors that affect obesity include:
- Single-gene mutations: Rare changes in a single gene can cause severe, early-onset obesity. The genes most commonly affected are the LEP gene — which makes leptin, a hormone that controls hunger — and the MC4R gene — which helps regulate appetite. The MC4R gene is often referred to as the obesity gene.
- Polygenic obesity: In most cases, people with obesity have multiple small genetic differences, each of which adds a small risk. These genes can affect how the body stores fat, how it uses energy and how hungry it feels.
- Brain function genes: Many of the obesity-related genes are active in the brain, especially affecting the areas that control hunger, fullness and reward. As a result, genetics can influence how much someone wants to eat and how satisfied they feel after eating.
- Gut Hormone regulation: If an existing condition affects hormone regulation, it can affect the ability to lose weight. Hormones like leptin and ghrelin, which signal hunger and fullness, are often affected by genetics, making it harder for some people to control their appetite.
While genes may predispose a person to obesity, environmental factors, individual behavior and other biologic factors (e.g., hormones, metabolism) determine how these are expressed.
How Environmental Factors Influence Obesity
A family history of obesity can increase the risk, although it is primarily due to lifestyle and environmental factors rather than genetics alone. Convenient food options and limited opportunities for physical activity can shape eating and activity patterns, making unhealthy choices more common.
Environmental factors are the conditions and habits that can make it easier or harder to maintain a healthy weight. Some key environmental factors of obesity include:
- Diet: Eating foods high in calories, sugar and unhealthy fats can lead to weight gain over time. Today, fast food, sugary drinks and snacks are convenient and often more affordable than whole-food options.
- Physical activity: Not getting enough exercise or movement in daily life means the body burns fewer calories, making it easier to gain weight. When combined with an unhealthy diet, these two factors can quickly contribute to obesity.
- Stress: High stress levels can affect the hormones (e.g., cortisol), leading to increased appetite. Stress can also cause cravings for unhealthy foods as a comfort (through dopamine pathways in the brain).
- Sleep – not getting enough sleep can lead to → increases in ghrelin & cortisol (see below)
- Socioeconomic factors: Individuals with limited access to healthy nutritious foods, safe places to exercise or access to health education may have a higher risk of obesity. Neighborhood location and culture can also play a significant role.
- Medications (e.g., certain antidepressants such asSSRIs, antipsychotics, insulin, oral steroids)
The Connection Between Genes and Environment
The rising prevalence of obesity in recent decades has been linked to an “obesogenic” environment — or easy access to high-calorie foods with limited opportunities for physical activity. Even in these environments, not everyone becomes obese. This is where the genetic connection comes in — if someone has a family history of obesity or a specific gene, they are more likely to become or maintain an overweight status because of several factors working against them.
Genetics contribute to factors like appetite and hunger signaling basal metabolic rate (how many calories you burn at rest – which is also determined by muscle mass, age, sex)., Whereas the environment provides opportunities or triggers that can increase the risk. In the same vein, genetics can also influence how someone responds to their environment by determining how easily and where the excess unused energy is stored as fatand how well the body responds to exercise
So obesity is not purely a consequence of one’s genes and neither is it purely environmental, rather how the interplay between genes and environmental factors manifest itself in an individual.
Other factors that play a role in obesity by regulating appetite, metabolism, and fat storage:
- Leptin – satiety hormone produced by the fat stores that acts on the brain (some people have leptin resistance)
- Ghrelin – hunger hormone predominantly produced by the upper outer aspect of the stomach (varies a lot)
- Glucagon like Peptide -1 (GLP-1), Polypeptide YY (PYY) – are gut hormones produced by the small intestine in response to food that induce satiety
- Gastric Inhibitory Peptide (GIP) influences how the body stores and uses energy, playing a role in fat storage and metabolism as well as may enhance bone formation
- Insulin – promotes fat storage when chronically elevated
- Cortisol – stress hormone that increases fat deposition
- Thyroid hormones – regulate metabolism -higher levels burn more energy
NEAT: Non-exercise Activity Thermogenesis
NEAT = calories burned from spontaneous movement (fidgeting, pacing, posture changes).
Two genetically similar people can differ by 300–800 calories/day in NEAT alone.
Working on improving NEAT can help improving energy expenditure significantly without having to take time out (& the cost) involved in going to a gym.
SET POINT: Your body biologically defends its highest weight (referred to as “set point”)
GUT MICROBIOME: Some types of gut bacteria (gut microbiome) profiles extract more calories from the same food.
Studies show:
- “Obesity microbiomes” produce more calories and store more fat.
- Transferring gut bacteria from obese mice to lean mice made the lean mice gain weight without increasing food intake
Weight Loss Solutions at the Center for Weight Loss Surgery
While genetic obesity cannot be definitively cured, treatments and management strategies exist to help individuals on how they can best modify the environmental factors to control it.. At the Center for Weight Loss Surgery, Dr. Myur Srikanth or clinician Karli Berry, ARNP, will work with you to discuss your weight loss goals and options, whether surgical or nonsurgical.
Weight Loss Surgery
The Center for Weight Loss Surgery specializes in robot-assisted and laparoscopic bariatric weight loss surgeries which can help control obesity life-long by altering the signaling between the gut and the brain with surgeries such as:
- Sleeve gastrectomy: During a sleeve gastrectomy, Dr. Srikanth removes nearly 90% of the stomach, reducing its size while its function remains normal since the anatomy is not altered in any other way.
- Duodenal switch:A duodenal switch removes the most stretchable portion of the stomach and reroutes the intestines, restricting food consumption and calorie absorption.
- Gastric bypass: In a gastric bypass, Dr. Srikanth creates a small pouch on the stomach and bypasses a top section of the small intestine to restrict food consumption.
- Adjustable gastric band: Through a Lap-Band® bariatric surgery, Dr. Srikanth places an inflatable band around the top of the stomach, creating resistance to eating and translating it into a sense of fullness.
Medical Weight Loss
Medical weight loss is a nonsurgical alternative for individuals seeking to lose weight. Our clinicians manage this medically supervised program to help individuals discover lifestyle changes, diets and medications that work for them. Patients may qualify if they have a body mass index (BMI) of 27 or higher. Together, we can develop a tailored program based on a patient’s individual needs, goals, body composition and nutritional intake.
Take the First Step Toward Healthy Living With the Center for Weight Loss Surgery
The Center for Weight Loss Surgery team recognizes that weight loss is more than a one-size-fits-all solution. Whether genetics or environmental factors are impacting your health, we can help you take the reins and achieve your weight loss goals.
Contact us to schedule a consultation today.
