Latest NHS England data from the Health Survey for England 2024 shows that two-thirds (66%) of adults in England are living with obesity or are overweight. Furthermore, 70% of adults had a waist-to-height ratio above the recommended level of 0.5, indicating higher levels of abdominal fat, central adiposity, and associated metabolic risks.
In response, weight loss experts at Tonic are urging people to look beyond BMI when assessing long-term health, highlighting the growing interest in biological age.
Unlike chronological age, which refers simply to the number of years a person has lived, biological age describes how well the body is ageing internally. It can be influenced by factors such as weight, waist size, fitness, muscle mass, blood sugar, sleep, lifestyle, and overall metabolic health.
A person’s biological age may be higher or lower than their chronological age, depending on how their body is functioning.
Jordan Chadwick, Director at Tonic, explains why health should not be reduced to a single number: “BMI can still be useful as a quick screening tool, but the problem comes when people treat it as a complete verdict on their health. It was never designed to explain the full picture, and on its own it can miss some of the most important details. Two people can have the same BMI and be in very different places health-wise. One person may have more muscle, better fitness, and stable blood sugar, while another may be carrying more weight around the waist and have a higher level of metabolic risk. That is why looking only at height and weight can be too blunt.”
Because BMI screening tools cannot distinguish between muscle and fat or show where fat is carried, experts recommend treating BMI as just one part of the overall picture and focusing on habits that support healthier ageing over time.
6 lifestyle changes to support healthier ageing
Experts at Tonic have outlined six actionable lifestyle changes that may help support healthier ageing and reduce factors associated with biological ageing:
Monitor your waist, not just the scales
Abdominal fat is closely linked to metabolic risk. Monitoring waist size alongside weight can provide a broader picture of long-term health.
“A healthier weight can reduce strain on the body, but the route matters. If someone loses weight in a way that is too restrictive or unsupported, they may struggle to keep it off. Sustainable change usually comes from a plan that protects nutrition, supports movement, and fits real life,” says Chadwick.
Prioritise muscle for long-term function
Maintaining muscle supports strength, mobility, and metabolism, all of which become increasingly important with age.
“Muscle is central to the bigger health picture. It supports strength, mobility and metabolism, which become increasingly important as we age,” Chadwick added. “If we only look at BMI, we miss the things that tell us how well the body is coping day to day.”
Incorporate daily movement
Physical activity does more than burn calories; research using epigenetic tools shows that higher BMI, elevated glucose, and poorer blood pressure profiles are associated with faster biological ageing. Regular movement improves insulin sensitivity, cardiovascular fitness, strength, and mood.
“Movement should not be framed only to burn calories. Regular activity helps improve insulin sensitivity, cardiovascular fitness, strength and mood, all of which influence how well the body functions over time. Even small increases in movement can make the wider plan easier to maintain.”
Manage blood sugar early
Elevated glucose is linked to accelerated biological ageing in epigenetic studies. Steady blood sugar impacts energy, hunger, cravings, and long-term metabolic risk.
“Maintaining steady blood sugar levels is vital for metabolic health. Blood sugar can affect energy, hunger, cravings and long term metabolic risk, so it’s worth paying attention to at every stage of life rather than treating it as something to worry about later.”
Prioritise sleep in your routine
Sleep underpins appetite regulation, mood, recovery, energy, decision-making, and resilience. Consistently poor sleep makes maintaining healthy habits significantly harder.
“Sleep is one of the first things people sacrifice, but it underpins appetite, mood, recovery and decision making. If someone is exhausted, it becomes much harder to move regularly, plan meals and make consistent choices. Poor sleep can quietly undermine the whole process.”
Protect your mental well-being
Constant pressure regarding weight, food, or appearance can be counterproductive. Sustainable health changes require support, realistic expectations, and psychological well-being.
“The mental side of weight loss is just as important as the physical side. If people feel ashamed, rushed or constantly judged by numbers, they are less likely to build habits that last. The aim should be support, structure and confidence, not pressure.”
Looking beyond the numbers
While the focus on biological age can encourage greater health awareness, Chadwick cautions against allowing it to become another figure to obsess over.
“Losing weight is never just about making the number on the scales smaller. The real question is whether the body is becoming healthier as a result. That is why quick fixes can be so misleading. Someone can lose weight quickly but still feel exhausted, unsupported, and unable to maintain the change. A healthier approach looks at what is happening underneath: metabolism, movement, nutrition, sleep, and the mental side of weight loss.”