Weight gain can be frustrating, especially when you are putting in consistent effort with diet and exercise but still not seeing meaningful changes. In many cases, this comes down to understanding how fat is stored, how it is mobilized, and what internal factors may be interfering with progress.
To approach weight loss effectively, it is important to move beyond surface level explanations and look at the underlying biology.
What Are Fat Cells and What Do They Do?
Body fat is stored in adipose tissue, which is made up of specialized cells called adipocytes. These cells store energy in the form of triglycerides, which are composed of fatty acids and glycerol.
Fat storage and breakdown are dynamic processes:
- Lipogenesis is the process of storing energy, where excess calories are converted into triglycerides and stored in adipocytes
- Lipolysis is the breakdown of triglycerides into free fatty acids and glycerol, which can then be used for energy
Adipocytes are not just passive storage units. They function as endocrine cells and release signalling molecules called adipokines, including leptin and adiponectin, which influence appetite, insulin sensitivity, and inflammation.
Where Is Fat Stored?
Fat is stored in different compartments in the body, and the location matters.
Subcutaneous Fat
This is the fat located just under the skin. It serves as an energy reserve, provides insulation, and has a relatively lower impact on metabolic health compared to deeper fat stores.
Visceral Fat
This fat is stored around internal organs such as the liver, pancreas, and intestines. Visceral fat is metabolically active and plays a direct role in disease development.
Visceral fat contributes to metabolic dysfunction through several mechanisms:
- It releases inflammatory cytokines such as tumour necrosis factor alpha and interleukin 6
- It drains into the portal circulation, meaning its byproducts go directly to the liver
- It promotes insulin resistance, impairing glucose metabolism
Fat accumulation in the liver is referred to as non alcoholic fatty liver disease. This can impair hepatic metabolism, affecting how the body processes nutrients, hormones, and medications.
Do We Lose Fat Cells or Just Shrink Them?
In most cases, weight loss reduces the size of fat cells rather than their number.
When the body is in an energy deficit:
- Stored triglycerides are broken down through lipolysis
- Fat cells shrink as their contents are used for energy
However, the number of fat cells generally remains stable in adulthood. This helps explain why weight regain can occur more easily after weight loss. The cells are still present and can refill when energy intake exceeds energy expenditure.
Hormonal Regulation of Fat Loss
Fat loss is not simply a matter of calories. Hormones play a central role in determining whether the body stores or releases energy.
Insulin
Insulin is a key storage hormone. It promotes glucose uptake into cells and inhibits lipolysis. Chronically elevated insulin levels, often seen in insulin resistance, can make fat loss more difficult.
Leptin
Leptin is produced by fat cells and signals satiety to the brain. In individuals with excess body fat, leptin resistance can occur, where the brain does not respond appropriately to leptin signals, leading to increased hunger and reduced energy expenditure.
Ghrelin
Ghrelin is known as the hunger hormone. It increases appetite and tends to rise during periods of caloric restriction, which can make sustained weight loss challenging.
Cortisol
Cortisol is released in response to stress. Chronic elevation can promote fat accumulation, particularly in the abdominal region, and may also contribute to muscle breakdown.
Metabolic Adaptation and Weight Loss Plateaus
One of the most important and often overlooked concepts in weight loss is metabolic adaptation.
As body weight decreases:
- Resting metabolic rate can decline
- The body becomes more energy efficient
- Appetite regulating hormones shift to promote increased intake
This is a protective mechanism. The body is attempting to preserve energy stores. However, this adaptation can make continued weight loss more difficult and contributes to plateaus.
Why Weight Loss Can Be Resistant
If weight loss is not occurring despite consistent effort, it is important to consider underlying contributors.
Insulin Resistance
Insulin resistance is one of the most common drivers of weight gain and resistance to fat loss. Elevated insulin levels impair lipolysis and favour fat storage.
Thyroid Dysfunction
Low thyroid function can reduce metabolic rate. Symptoms may include fatigue, constipation, dry skin, and hair thinning. Assessment typically includes TSH, free T4, and free T3.
Cortisol Dysregulation
Chronic stress or conditions such as Cushing’s syndrome can lead to persistently elevated cortisol, contributing to central fat accumulation and muscle loss.
Polycystic Ovary Syndrome
PCOS is strongly associated with insulin resistance, even in individuals with a normal body weight. This can promote fat storage, particularly in the abdominal region, and disrupt hormonal balance.
Sleep and Circadian Rhythm
Sleep deprivation alters leptin and ghrelin levels, increasing hunger and reducing satiety. Poor sleep is also associated with reduced insulin sensitivity.
Mental Health
Depression and chronic stress can influence physical activity, dietary patterns, and hormonal balance, all of which impact weight.
Medication-Induced
Certain medications can contribute to weight gain through increased appetite, fluid retention, or metabolic changes. This includes some antidepressants, antipsychotics, and corticosteroids.
Chronic Inflammation
Low grade inflammation can impair insulin signalling and contribute to metabolic dysfunction. Markers such as CRP and ESR may be elevated in these states.
Practical Strategies That Align With Physiology
Understanding the biology allows for more targeted strategies.
Nutrition
A balanced dietary pattern that includes adequate protein, fibre, and healthy fats supports satiety and metabolic health. Protein intake helps preserve lean muscle mass during weight loss, which is important for maintaining metabolic rate.
Exercise
- Resistance training supports muscle mass and improves insulin sensitivity
- Aerobic exercise enhances mitochondrial function and energy utilization
General guidelines recommend at least 150 minutes of moderate intensity or 75 minutes of vigorous activity per week.
Sleep
Adequate sleep supports hormonal balance, particularly leptin and ghrelin, and improves metabolic function.
Consistency
Sustainable progress is driven by consistent habits over time. Short periods of extreme restriction are less effective than long term adherence to balanced lifestyle changes.
Final Thoughts
Fat loss is not just about willpower or effort. It is a complex interaction between energy balance, hormones, and metabolic adaptation.
In many cases, resistance to weight loss is not a failure of discipline but a reflection of underlying physiology. Identifying and addressing contributing factors, while maintaining consistent lifestyle habits, provides the most effective and sustainable path forward.
As always, it is important to work with a qualified healthcare provider to determine what approach is most appropriate for your individual health needs.
About the author:
Hi, I’m Abinaa, a fourth-year naturopathic medical student at the Canadian College of Naturopathic Medicine with a deep-rooted passion for natural healing, inspired by my South Asian upbringing. Through this blog, I hope to share my journey, explore topics in holistic health and wellness, and offer simple, thoughtful insights that support a more balanced and mindful way of living.
