Published: 12:52 BST, 14 August 2026 | Updated: 12:52 BST, 14 August 2026
Overweight and obesity is perhaps the biggest risk factor for some of the UK's biggest killers – heart disease, dementia and many types of cancer.
Then there's the impact of excess weight on the joints, bones and respiratory system, increasing the risk of debilitating conditions like arthritis and asthma.
Now, with the advent of highly effective slimming injections, Britain is seeing more weight loss transformations than ever before. But does a sudden shifting of several stone reverse the damage of years of obesity?
The impact of extra weight is, after all, significant.
'Obesity generally leads to higher blood glucose levels, and this extra circulating sugar causes body-wide damage,' says Stuart Gray, a professor of muscle and metabolic health at the University of Glasgow.
'Much of this damage affects the heart and blood vessels. If it progresses to diabetes, you could face damage to your kidneys as well as nerves in the feet and eyes.
'Excess body weight also tends to mean you have higher blood fat levels, which can lead to plaques in the blood vessels, narrowing the blood vessels and putting even more strain on your heart.’
So at what point in life is this damage set in stone – regardless of a change in lifestyle – and when is a healthy weight most crucial? Here, experts reveal the 'sweet spot' in life when it's most beneficial to be slim.
In the UK, nearly two-thirds of adults are overweight, and more than a quarter are obese
The damage done by carrying excess weight begins roughly five years into obesity, according to a 2020 UK study.
However after a decade, the risk of heart disease as well as heart-related death climbs significantly.
A US study following 5036 people found those who spent between five and 14 years with obesity had roughly a 94 per cent higher risk of early death compared to those who'd never been obese.
However, Prof Gray says the danger applies to those who are overweight for long periods of time, too.
'It's the cumulative exposure to excess weight that's the problem,' he says. ‘If you've had 10 or 15 years of being overweight or living with obesity, then the inflammation, vascular dysfunction [blood vessel damage] and high glucose levels will have caused some damage that you can't get rid of.'
