As an endocrinologist, today I am going to discuss a topic which is often misunderstood: that only overweight individuals are at risk of developing insulin resistance and prediabetes. 

First, let us understand what insulin resistance is. It occurs when the body’s cells don’t respond effectively to insulin, a hormone that regulates blood sugar levels. Over time, this can lead to elevated blood glucose and eventually type 2 diabetes. While excess weight is a known risk factor, it is not the sole issue. 

When I mention insulin resistance or pre-diabetes in my practice, many patients immediately respond, I am not overweight. This common misconception is that only those who are overweight develop these metabolic conditions can lead to delayed diagnosis and treatment for many individuals. 

I have treated many patients who we call normal weight metabolic obesity. These individuals maintain a healthy BMI but have significant metabolic dysfunction. 

Let me explain this more. 

We know insulin is the hormone produced by the pancreas that allows glucose, your body’s primary fuel, to enter your cells. When cells become resistant to insulin’s action, blood glucose levels rise, forcing your pancreas to produce more insulin to compensate. Insulin resistance is the precursor to type 2 diabetes. 

Insulin resistance develops when cells, especially muscle, fat, and liver cells, become less responsive to insulin. Even without obesity, factors like ectopic fat deposition, mitochondrial dysfunction, and chronic low-grade inflammation can impair insulin signalling. 

While obesity is certainly a risk factor, approximately 20% of people with insulin resistance have a normal body weight. These individuals often have what we call Thin outside, fat inside meaning they will have a normal external appearance but excessive visceral fat surrounding their internal organs. This visceral fat is metabolically active tissue that secretes inflammatory compounds, disrupting normal insulin signalling. 

Several factors can contribute to insulin resistance in lean individuals:

• First, genetics plays a significant role. Some people inherit a predisposition to insulin resistance regardless of their weight. Certain ethnic backgrounds, including South Asian, East Asian, and Hispanic populations, have lower BMI thresholds. 
• Secondly, body composition matters more than weight alone. A person with low muscle mass but higher body fat percentage, sometimes called skinny fat, may develop insulin resistance despite a normal weight. 
• Third, lifestyle factors are crucial. Sedentary behaviour, poor sleep quality, chronic stress, and diets high in refined carbohydrates can promote insulin resistance independent of BMI.
• And the last is certain medical conditions like polycystic ovary syndrome, Cushing’s syndrome and lipodystrophy can cause insulin resistance without obesity. 

You can look out for these warning signs even at a normal weight:

• Dark patches of skin on the neck, armpits, or groin. 
• Increased triglycerides and decreased HDL cholesterol
• Unexplained fatigue, especially after meals
• Intense carbohydrate cravings
• For women, irregular menstrual cycles 

Interventions like regular exercise, having a balanced diet, adequate sleep optimisation, stress management techniques and also medicational support. 

I recommend that it is best to get screening for insulin resistance with an oral glucose tolerance test and fasting insulin levels for anyone with a family history of diabetes, regardless of weight. 

Remember, you cannot rely on the mirror or scale alone to assess metabolic health. By understanding that insulin resistance can affect anyone regardless of weight, we can better identify, prevent, and treat this condition before it progresses to diabetes and its complications. 


Kripa, is a Specialist Dietitian at The London Obesity & Endocrine Clinic. She has helped many patients overcome weight management barriers. ©Simplyweight

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