
A recent podcast featuring Dr Caroline Low, an anti-ageing physician, has reignited conversations around insulin and metabolism.
Speaking on entrepreneur Shulin Lee’s podcast, Dr Low claimed that insulin is the only hormone that increases with age, describing it as the “winter hormone” that stores sugar as fat. She also suggested that cardio is the only way to lower insulin, which is why marathon runners can eat large amounts of carbohydrates after a run without storing them as fat.
While regular exercise is undoubtedly beneficial for metabolic health, are these claims scientifically accurate? According to Dr Sukirti Misra, Consultant Endocrinologist, KIMS Hospitals, Thane, “The statement oversimplifies the issue. Insulin isn’t the only hormone that changes with age, and it doesn’t consistently rise in everyone.”
She explains that several hormones, including growth hormone, testosterone, estrogen and DHEA—typically decline with age, and cortisol patterns may also change.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
“What often increases is insulin resistance, especially when people gain weight, lose muscle mass and become more sedentary. In response, the pancreas may produce more insulin to keep blood sugar levels under control,” she says.
Dr Misra says this is another misconception. “Cardio certainly improves insulin sensitivity, but it isn’t the only method. Resistance training, weight loss, quality sleep, stress management and a balanced diet all significantly reduce the body’s demand for insulin,” she explains.
“Regular aerobic exercise improves insulin sensitivity because contracting muscles take up glucose more efficiently, even when insulin levels are lower,” says Dr Misra.
This glucose is then used to replenish glycogen stores in muscles instead of remaining in the bloodstream. However, she cautions against the popular belief that carbohydrates are automatically converted into body fat.
“Carbohydrates don’t immediately become fat. They are first used for energy or stored as glycogen in the liver and muscles. Fat storage generally occurs when calorie intake consistently exceeds the body’s energy requirements, regardless of whether those calories come from carbohydrates or fats,” she explains.
According to Dr. Misra, the body decides whether to burn or store energy based on multiple factors—not just insulin.
“Total calorie intake, meal composition, muscle mass, genetics, sleep quality, stress levels and overall metabolic health all influence how the body manages energy,” she says.
She adds that meals rich in fibre, lean protein and healthy fats produce a steadier rise in blood glucose than refined carbohydrates. Meanwhile, building muscle through resistance training increases glycogen storage capacity, making it less likely that excess calories will be stored as fat.
For people with insulin resistance, prediabetes or type 2 diabetes, Dr Misra recommends a comprehensive lifestyle approach rather than relying on a single type of exercise.
“The ideal strategy combines at least 150 minutes of moderate aerobic exercise every week with two to three strength-training sessions,” she says. She also recommends eating a diet centred on vegetables, whole grains, legumes, lean protein and healthy fats while limiting ultra-processed foods and sugary drinks.
“Losing even 5-10% of body weight can significantly improve insulin sensitivity. Good sleep, stress management and regular medical follow-ups are equally important,” she says.