> ## Content Index > Fetch the complete content index at: https://www.alphabetguides.com/llms.txt > Use this file to discover other available public pages before exploring further. # Do These Genes Make Me Look Fat? The Genetics of Obesity - URL: https://www.alphabetguides.com/fat-genes/ - Published: 2026-08-27T08:00:53.000Z - Updated: 2026-08-27T08:00:53.000Z - Description: Genes influence how much body fat you have and how easily you lose (or gain) it. However, they don't make you obese or stop you from losing fat. - Author: Dr. Robert Davies - Tags: Fat Loss, #pin, #link, Health --- key takeaways - Your genes influence appetite, metabolism, fat storage and exercise capacity, but they can also interact with lifestyle and environment. - Having “fat genes” does increase your susceptibility to obesity, but it doesn't guarantee it or prevent you from losing fat. - Your environment and lifestyle can moderate how your fat genes affect your body fat levels. You should work with your genetic strengths. --- Your genetics are a strong determinant of your [body weight](https://www.alphabetguides.com/tag/fat-loss/), but they do not determine all of it. Understanding the role your genes have in how easily you can lose (or gain) fat will give you a bit of insight into why people respond differently to the same programme. It will also prevent that fatalistic thinking that you're just a product of your genes. That said, it is true that there *is* a genetic component to obesity. Your genes have been shown to determine around 40-50% of your body weight. The genetic component is lower in people who are of normal weight (i.e., genes determine around 30% of body weight) compared to those who are obese (i.e., genes determine around 70% of body weight). **But there is no single “fat gene”.** Your body weight (and body fat levels) are influenced by hundreds of different genes. These genes combine and exert a significant influence on how you regulate your weight and fat tissue. Your genes also interact with your environment, meaning certain genes only exert work under certain circumstances (e.g., high or low calorie intake, sedentary or [active](https://www.alphabetguides.com/tag/exercise/) lifestyles, high or low [stress](https://www.alphabetguides.com/what-is-cortisol/) states, etc.). Your lifestyle decisions can also influence whether your genes are active or not. This tells us that your genes are influential, but they *don’t* determine whether you lose, gain or maintain body fat. Having “fat genes” *does* increase your susceptibilityto gaining fat and makes fat loss more difficult. However, having these genes *doesn't* guarantee that you will be fat or that you *can’t* lose fat at all. **You are more than your genes.** ## How Genes Affect Your Appetite Several genes are thought to affect your [appetite](https://www.alphabetguides.com/appetite-and-body-weight/), satiety levels and food-reward responses. For example: - A variant of the “*FTO"* gene (found in most people) is *associated* with increased appetite and preferences for [calorie-dense foods](https://www.alphabetguides.com/why-ultra-processed-foods-become-popular/). - A variant of the "*MC4R*" gene can lead to very strong, incessant hunger. This is thought to be one of the most powerful “fat genes” around. - Variants in the “*POMC*" gene are *associated* with more hunger and more frequent eating behaviour. Variations in the genes that regulate “satiety hormones” can trick your brain into thinking you need to eat more energy than you actually need. Whereas“hunger gene” variants encourage you to snack more and eat more frequently. ## How Genes Affect Energy Expenditure The amount of energy you “burn” while you rest, work, [sleep](https://www.alphabetguides.com/tag/sleep/), or exercise can vary by hundreds of calories a day. Forty to 80% of the amount of energy you burn (just to keep you going) is influenced by your genes. How efficiently your cells use energy, the number of mitochondria you have, the size of your organs and how active they are, are all influenced by your genes. Thyroid [hormone](https://www.alphabetguides.com/tag/hormones/) is the key regulator of your "metabolic rate". So, differences in some of the genes that regulate it can either increase or decrease thyroid function and thus your metabolic rate. Variations in the "*UCP1"*gene can alter the amount of heat you produce, which means people who “run hotter” will burn more calories. Some genes are also associated with restlessness, fidgeting and the ability to maintain posture, and thus people who have them will generally burn more calories than people who don't. ## How Genes Affect Fat Storage Besides influencing how much fat tissue you have, your genes also influence *where* you store fat and *where* you lose it from when you burn it (e.g., *STLM* gene). This is important as *where* the fat is stored can impact both your health risk and what you look like. Your genes can also influence whether you store fat around your abdomen (higher health risk) or your hips and thighs (lower health risk) (e.g., *TBX15* and *HOXC13* genes). The most obvious difference lies in how men and women store fat, due to sex-specific genes (e.g., *VEGFA* gene). Your genes also influence whether fat is stored around your organs, known as “visceral” fat (e.g., *PPARG* gene). Even a normal-weight person can be genetically predisposed to storing large amounts of visceral fat. This can also explain why people lose fat from different places, at different rates. Think about those stubborn muffin tops that never seem to go away no matter how much fat you lose. Lastly, your genes can also influence the number of fat cells you have and how much energy they can store — so they go on to affect your “storage” capacity of fat. Those with greater storage capacity *may* put on fat more easily and find it more difficult to lose it. [Visceral Fat & Health: Not All Fat is Created EqualVisceral fat is stored around organs. Internal fat is metabolically active and releases substances that are bad for your cardiometabolic health.![](https://storage.ghost.io/c/69/dc/69dcec6d-c40d-40e8-823a-e4ec7bb45b10/content/images/icon/Logo--Square--1-eeef48f9-8e5e-41d9-a18c-0b7e09ceadbc.png)Alphabet GuidesDr. Robert Davies![](https://storage.ghost.io/c/69/dc/69dcec6d-c40d-40e8-823a-e4ec7bb45b10/content/images/thumbnail/photo-1634463278803-f9f71890e67d-b1221270-1c13-44a9-96fe-1a8069441bf1.jpeg)](https://www.alphabetguides.com/visceral-fat/) --- ## How Genes Affect Your Diet and Exercise Habits ### Diet Your genes also exert control over how different people respond to different diets. Differences in the genes that regulate carbohydrate metabolism are *associated* with how well you [handle carbs](https://www.alphabetguides.com/keto-diet/). This means that some people may be able to lose fat whilst eating different amounts of carbohydrates. The same applies to fat metabolism. Some people are genetically predisposed to burn more fat, more efficiently than others. This means they can consume more [dietary fat](https://www.alphabetguides.com/low-fat-diet/) without negatively impacting their body fat and health. This is one of the reasons why the [low-carb](https://www.alphabetguides.com/atkins-diet/) or [low-fat](https://www.alphabetguides.com/low-fat-diet/) diets don't seem to work for everyone. ### Exercise & Physical Activity Several genes are also associated with how you respond to physical activity and exercise, and your ability (or motivation) to exercise and be active. So some lucky people naturally have good exercise capacity and adapt to exercise very easily. These people may lose more fat more easily. But, unfortunately, some people are not as genetically gifted and will lose less fat. Genes can also influence how quickly you recover from exercise, your potential injury risk, how your joints and connective tissues strengthen (or not) and how your inflammation is controlled after your exercise. These all affect how your [muscles](https://www.alphabetguides.com/tag/muscle/) repair and grow in response to exercise, which go on to affect your body fat levels. ## How Genes Affect Your Behaviour Through dopamine and other brain chemicals, your genes can influence the processes that impact how much you enjoy exercise, eating, certain foods, your willpower, discipline, motivation, and other lifestyle preferences or your personality. All these can go on to potentiallyinfluence how well you can follow (and succeed) when you make a new lifestyle change. Some genes are associatedwith your response to [calorie restriction](https://www.alphabetguides.com/hara-hachi-bu-an-ancient/), your body fat levels, and the ease with which you can lose weight. So even if you start to successfully lose weight, your genes may make it more difficult to continue or maintain it. They can also influence your appetite, your emotional relationship with food, and your metabolic rate, making continued fat loss easy or more challenging. ## Nature vs. Nurture There is little you can change when it comes to your genes. But you *can* control your environment and how your genes interact with it. Exposure to “obesogenic” environments with easy access to [junk foods](https://www.alphabetguides.com/how-to-avoid-upfs/), activities where you sit down a lot, and high stress can amplify genetic predisposition to eat more, move less and gain fat (or fail to lose fat). Being physically active and exercising regularly can reduce the negative influences of those of us who have “fat genes”. Some specific diets (e.g., high in added sugar and [ultra-processed foods](https://www.alphabetguides.com/ultra-processed-food-diet/)) may amplify weight gain for people with "fat genes". And the same applies to high stress and poor sleep. Understanding that your environment *can* affect your genetic predispositions (both positively and negatively) should empower you to focus on optimising your environment if you want to lose fat. Aim to minimise the impact of your genetic vulnerabilities whilst leveraging your genetic strengths; do both at the same time. --- ## Bottom Line Hundreds of genes influence appetite, metabolism, fat storage, and exercise responses, but they can interact with lifestyle and environment. Having “fat genes” increases susceptibility but doesn't guarantee obesity or prevent fat loss. Genetic variants affect how you eat, move, store fat, your appetite, metabolic rate, fat distribution, and the response to different diets and exercise programmes. Your environment and lifestyle choices can amplify or buffer genetic risk. You can also leverage your genetic strengths for successful, sustainable fat loss. [Fat LossLosing fat and reaching a healthy weight comes down to biology, behaviour, and environment. Get diet, nutrition, and exercise strategies for fat loss.![](https://storage.ghost.io/c/69/dc/69dcec6d-c40d-40e8-823a-e4ec7bb45b10/content/images/icon/Logo--Square--1-89c61ece-213d-4c5a-894a-837f8e88f7b7.png)Alphabet Guides![](https://storage.ghost.io/c/69/dc/69dcec6d-c40d-40e8-823a-e4ec7bb45b10/content/images/thumbnail/photo-1689446803604-828dad725fd0-57bf8702-6f43-42cf-b053-17de4df4824d)](https://www.alphabetguides.com/tag/fat-loss/) --- #### Sources 1. Bouchard C. Genetics of Obesity: What We Have Learned Over Decades of Research. Obesity (Silver Spring). 2021 May;29(5):802-820\. PMID: [33899337](https://pubmed.ncbi.nlm.nih.gov/33899337/?ref=alphabetguides.com) 2. Chamarthi VS, Daley SF. Genetic and Syndromic Causes of Obesity: Diagnosis and Management. \[Updated 2025 Sep 15\]. In: StatPearls \[Internet\]. Treasure Island (FL): StatPearls Publishing; 2026 Jan. Available from: [https://www.ncbi.nlm.nih.gov/books/NBK573068/](https://www.ncbi.nlm.nih.gov/books/NBK573068/?ref=alphabetguides.com) 3. Heid IM et al. Meta-analysis identifies 13 new loci associated with waist-hip ratio and reveals sexual dimorphism in the genetic basis of fat distribution. Nat Genet. 2010 Nov;42(11):949-60\. PMID: [20935629](https://pmc.ncbi.nlm.nih.gov/articles/PMC3000924/?ref=alphabetguides.com) 4. Locke AE et al. Genetic studies of body mass index yield new insights for obesity biology. Nature. 2015 Feb 12;518(7538):197-206\. PMID: [25673413](https://pubmed.ncbi.nlm.nih.gov/25673413/?ref=alphabetguides.com) 5. Loos RJF, Janssens ACJW. Predicting Polygenic Obesity Using Genetic Information. Cell Metab. 2017 Mar 7;25(3):535-543\. PMID: [28273476](https://pubmed.ncbi.nlm.nih.gov/28273476/?ref=alphabetguides.com) 6. Rankinen T et al. The human obesity gene map: the 2005 update. Obesity (Silver Spring). 2006 Apr;14(4):529-644\. PMID: [16741264](https://pubmed.ncbi.nlm.nih.gov/16741264/?ref=alphabetguides.com)