Most people rarely think twice about an extra biscuit with tea, a sugary coffee on the go, or a midweek takeaway treat. However, new research suggests these small daily indulgences may do more than expand your waistline—they could also accelerate ageing and shorten your life.
Moderate Calorie Restriction Yields Significant Health Benefits
Scientists have found that simply cutting daily calorie intake by around 10 to 15 per cent can improve heart health, blood sugar control, and blood pressure. These improvements are linked to a lower risk of age-related diseases.
The findings come from the CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy) study, a major US research project published in the American Journal of Clinical Nutrition. In the study, 143 healthy adults attempted to reduce their calorie intake by 25 per cent over two years, while a comparison group continued eating normally.
In reality, participants achieved an average reduction of about 12 per cent. Researchers say that was still enough to produce meaningful health benefits. Those in the calorie-restricted group experienced lower blood pressure, improved insulin sensitivity, reduced cholesterol levels, and around 10 per cent weight loss. Crucially, these changes were observed even in people who were not overweight at the start.
Realistic Reduction Achievable for Most People
Dr Sai Krupa Das, senior scientist at Tufts University and one of the study authors, described the results as encouraging because the level of restriction is realistic. 'The most exciting part is that we saw these benefits with only a moderate level of restriction that's feasible for most people,' she said.
For someone consuming around 2,000 calories a day—the NHS guideline for an average adult woman—this means cutting just 200 calories daily. That is roughly equivalent to a large glass of wine, a packet of crisps, or a glazed doughnut. Researchers emphasise that the reduction does not have to be strict or extreme; it can be spread across the week or achieved through small swaps, such as cutting snacks or sugary drinks.
How Calorie Restriction May Slow Ageing
Scientists believe the benefits may stem from how the body processes energy. When calorie intake drops, the body becomes more efficient at converting food into energy and may produce fewer 'reactive oxygen species'—unstable molecules linked to cell damage, ageing, and diseases such as cancer and Parkinson's. Tests on participants suggested that those cutting calories had lower levels of these molecules compared with the control group.
Experts stress that the findings do not guarantee calorie restriction will lead to a longer life, but they do strengthen the link between eating patterns and healthy ageing. The CALERIE researchers are now following up participants years later to see whether the early health improvements have lasting effects and whether people continued the calorie-reduction habits after the study ended.
Safety Considerations and Guidance
Scientists say moderate calorie reduction may be safe for many healthy adults, but it is not suitable for everyone. Those advised to seek medical guidance first include people over 65, pregnant women, children and teenagers, individuals with low body weight, and those with medical conditions affecting bone density or requiring medication. Dr Das recommended using online tools to estimate current intake before making small reductions: 'Use that, and then take off 10 or 20 per cent.'
Broader Context of Obesity and Health
The findings come as obesity rates continue to climb. In England, nearly two-thirds of adults are now overweight, with more than a quarter classed as obese—around 14 million people. The condition costs the NHS more than £11 billion a year, alongside wider economic losses linked to ill health and reduced productivity. Meanwhile, fewer than a third of adults eat the recommended five portions of fruit and vegetables a day, and around one in three do not get enough physical activity.
Understanding Calorie Needs
Calories measure the energy in food and drink, listed as 'kcal' on packaging. When we consume more calories than we use, the body stores the excess as fat, which over time can lead to weight gain. Knowing calorie content helps track daily intake, but counting calories is not the only approach. Adjusting portion sizes and ensuring meals contain the right types of food also make a significant difference.
The recommended daily calorie intake is 2,500kcal for men and 2,000kcal for women. For weight loss, the average person should aim to reduce daily intake by about 600kcal, bringing it to 1,900kcal for men and 1,400kcal for women.
