Weight Loss

How Biology Really Affects Your Weight

Key Takeaways

Key takeaways:

  • Weight regulation is influenced by a complex combination of biological factors, including genetics, hormones, and metabolism.
  • Hormones like leptin and ghrelin play a crucial role in appetite control and energy balance.
  • Genetics can contribute to individual variations in weight and predisposition to obesity.
  • Metabolic rate, which is influenced by factors like age, muscle mass, and activity level, impacts calorie expenditure and weight management.
  • Understanding the biological factors involved in weight regulation can help inform personalized approaches to weight loss and maintenance, taking into account individual differences and challenges.

The factors influencing our body size are deeply intertwined and influenced by biological, genetic, environmental, hormonal, social, and health conditions. It's time to move beyond “move more and eat less” thinking. Let’s dive into the underlying aspects of weight management and ways to develop an effective plan for sustainable change. 

How it’s all connected

Examining the interrelated factors that determine our body size involves exploring our biology and learning how our genetics, hormones, metabolic rate, and health conditions all play a role. Genes are known to be significant determinants in body size and shape, as well as pre-dispositioning individuals to obesity or greater risk for eating disorders. Hormones can also play a significant role in weight gain and loss.

According to Harvard Medical School, too much cortisol can increase appetite and eventual fat storage. Metabolic factors are often affected by diet composition, physical activity, age, stress, and gender. 


Genetics is one of the primary factors to consider when examining the biology related to obesity and metabolic health. Our genetic makeup can go a long way in determining our body composition, influencing traits such as height, bone structure, muscle mass, fat storage, and a tendency towards obesity or an eating disorder. 

By understanding the various components of our genetic code, we can gain more insight into how our bodies work and move towards healthily managing our bodies. 


Hormones are another major factor in the biology related to obesity and metabolic health. Hormonal imbalances can cause metabolic shifts, leading to changes in appetite, cravings, and energy levels.  According to a recently updated study, hormones like leptin and ghrelin influence hunger signals in the body and disruption of these hormones can often cause abnormal eating patterns or cravings. 

Sex hormones such as estrogen and testosterone considerably affect fat distribution and muscle mass, essential for overall health and well-being. Understanding how our hormones work with our body's metabolic regulation processes can help us with our dietary, lifestyle, and physical activity behaviours.

Metabolic rate

Metabolic rate plays an essential role in the biology related to obesity and metabolic health. Your metabolic rate is determined by your lean body mass, age, sex, and activity level ,and influences how quickly calories are burned throughout the day. 

A high metabolic rate means more calories are burned faster; conversely, a slower metabolism results in fewer calories. Understanding your metabolic rate can be helpful for adjusting diet and exercise in order to hit your health goals. Genetics can also influence one's metabolic rate by influencing muscle composition, and by impacting the number of calories one burns off at rest and during physical activity.

Other health conditions

Other health conditions can have a significant impact on the biology related to obesity and metabolic health. Chronic illnesses such as diabetes and heart disease can cause fluctuations in metabolic health and body size due to changes in insulin levels and other metabolic processes. 

Mental health disorders such as depression or anxiety can lead to changes in appetite or energy levels that may affect one's physical activity and dietary behaviours.  

Even prescription medications or supplements can contribute to unexpected changes in body composition. It is essential to be aware of all potential factors when making sustainable adjustments to achieve maintainable health goals. .

How our environment and socioeconomic status can shape our weight

Where we live significantly impacts food access and available leisure activities, affecting someone’s ability to manage health and body size. 

According to the paper “Demographic and socioeconomic disparity in nutrition: application of a novel Correlated Component Regression approach,” socioeconomic status also contributes largely towards what types of food is available to people, as healthy options are often limited by cost. This can mean less nutritious diets and meal planning that doesn't help people reach their goals. 

The ability to access healthy foods, the cost of living, and healthcare access all play a role. Plus, lower-income people are less likely to have time for exercise or leisure activities due to long work hours or other financial burdens.

The opposite is true for those from a higher socioeconomic status. People with a higher-income often have access to many forms of physical activity, increased access to fresh fruits and vegetables, and access to other lifestyle opportunities and behaviours, resulting in better overall health outcomes.

A holistic approach to effective weight management

A holistic approach to effective weight management and health involves considering physical, mental, and emotional factors. On the physical side, it is essential to consider diet, physical activity, sleep patterns, and general lifestyle opportunities and behaviours. Maintaining a balanced diet of nutritious foods in appropriate portions can be vital in reaching health goals. 

Regular physical activity has been shown to increase energy levels while burning calories. Getting adequate, high-quality rest through good sleep hygiene is also essential for overall health and well-being.

Addressing any underlying emotional or mental health concerns that may be impacting your dietary or physical activity behaviours is also crucial. Seeking support from friends and family and professional counselling or therapy can help individuals better understand their behaviours as they relate to their health. 

A holistic approach can help you make sustainable changes for long-term success in reaching health goals.

Conclusion: it’s about more than just calories

The key to lasting weight management and metabolic health is to develop a customized plan tailored to your needs.

A holistic approach needs to consider physical, mental and emotional factors. Making small, sustainable changes, such as modifying dietary and physical activity behaviours, can also lead to successful outcomes. For some people, adding medication may be beneficial. Speak to a healthcare practitioner if you are interested in discussing potential options to help you reach your goals.

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