Five ways high-intensity interval training – or HIIT – benefits your health, beyond aesthetics and fitness

Every year the global fitness industry waits for the American College of Sports Medicine – a publication that has become the ultimate playbook for cutting-edge gyms and elite trainers – to publish its annual review of fitness trends.

Regular MF readers won’t be surprised to learn that high-intensity interval training (HIIT) is in that elusive list for 2025, just as it is year after year.

So what is that makes HIIT such a perennial hit? You may be surprised to learn that beyond the shred appeal and cardio fitness factor, there are also some serious health gains to be had.

FAT LOSS
The surge in levels of two hormones, epinephrine and norepinephrine from HIIT training stimulate the receptors that drive lipolysis, i.e. the release of fat for use as fuel.

This is a double whammy, as it reduces visceral fat around your organs, improving your health but also subcutaneous fat under the skin, helping you to achieve that cut.

CARDIO FITNESS
HIIT improves VO2 Max – your ability to absorb and use oxygen – by increasing the strength of heart muscle contractions, leading to more blood being pumped out with each beat.

Also, HIIT increases the number and size of mitochondria, often referred to as the powerhouses of the cells, due to their role in creating energy and influence on the ageing process.

INSULIN RESISTANCE
Insulin sensitivity describes the body’s ability to use the vital energy source, glucose, and research shows that it can be improved through HIIT.

This is due to muscle contractions stimulating shuttle transporters to take glucose into the working muscle from the blood. By maintaining the management of blood sugar levels, risk of type 2 diabetes is significantly reduced.

REDUCED CHOLESTEROL
HIIT brings a triple threat to help improve your heart health by reducing both potentially artery-clogging triglycerides and low-density lipoprotein, referred to as the ‘bad’ cholesterol due to its link to coronary disease and stroke.

In addition, HIIT elevates levels of high-density lipoprotein, known as the ‘good’ cholesterol, as it transports cholesterol to the liver to be flushed from the body.

BRAIN HEALTH
A study exploring the effects of HIIT on the brain found that it not only boosts cognitive function, making you more effective at both work and play, but may also help in the prevention of Alzheimer’s and Parkinson’s diseases.

That’s thought to be due to increased blood flow enhancing ‘cerebral oxygenation’, but also through increasing levels of a key protein called ‘brain-derived neurotrophic factor’.