Gut health reset: How belly fat is harming you and six eating changes that will reduce your waist size
You’re probably aware that as Britons, we’re getting fatter. But did you know we’re also getting wider? That’s much more than a beach body problem. Growing evidence has confirmed the association between waist circumference and the risk of serious preventable conditions, such as heart disease, type 2 diabetes and stroke.
Official figures revealed that in the first half of 2023, there were an extra 28,000 deaths in the UK. The biggest rise in unexpected deaths was in adults aged 50-64, who have increasingly been dying prematurely from preventable problems such as heart disease, diabetes and high blood pressure.
But instead of BMI, health bosses are increasingly focusing on waist circumference as a measure of these health risks. In April 2022, the National Institute for Health and Care Excellence (NICE) recommended that people with a BMI of under 35 measure their waist-to-height ratio to work out whether they’re carrying enough weight around the middle to predispose them to a higher risk of metabolic diseases. It advised keeping your waist measurement to half your height or less.
According to 2019 figures from the NHS, 59 per cent of men and 69 per cent of women have a higher-than-desirable waist circumference. The figures, covering the period from 1993 to 2017, revealed that the average waist size of an adult English woman was 35.2 inches, up three whole inches from 32.2 inches 24 years earlier. Men had an average waist size of 38.5 inches, up 2.2 inches from 36.7 inches in 1993.
But just as a widening waistline can increase your risk, taking steps towards a healthy diet and lifestyle to reduce your waistline can reduce your health risk, too. New research from King’s College London has found that following a healthy diet and lifestyle for 18 weeks led to a healthier waist circumference, reduced blood pressure, improved blood fats, weight loss, and improved gut microbiome composition.
The research, published in November 2023 in the journal Proceedings, was the result of a randomised controlled trial called the Zoe Method study. It took 347 people and split them into two groups. Half of them followed American population-based guidelines for a balanced diet based on the US government’s Myplate scheme. The other half followed a personalised nutrition and lifestyle plan co-created by Tim Spector, professor of genetic epidemiology at King’s College London.
“The participants in our group saw improvements in their blood lipids, their blood glucose control and their gut microbiome. But the most significant change was the reduction of 3-6cm in their waist circumference,” says Dr Sarah Berry, associate professor in nutritional sciences at King’s College London, chief scientist at Zoe, and co-author of the study.
The programme measures people’s gut microbiome, blood lipids and blood sugars, then recommends a nutrition programme for them. The Independent has teamed up with Zoe’s scientific team to bring you some of the key nutrition and lifestyle changes that worked to reduce waist size for people in the study.
Why reducing your waist matters
Nutrition and health researchers have moved away from body mass index (BMI) as a predictor of health. “One of the issues with BMI is that it does not take into account the distribution of body fat,” says Prof Spector.
“Visceral fat [fat around the middle] and liver fat are associated with increased cardiometabolic risk factors, including insulin resistance, high blood pressure, and poor blood fat profiles. Waist circumference (or more specifically, waist-to-height ratio – see above) is a better indicator of body composition, and is an easy, low-cost measure that clinicians can use to assess cardiometabolic risk.
“If you have a higher waist circumference, reducing this can have a measurable impact on improving your risk of cardiovascular disease and type 2 diabetes,” Prof Spector continues. “It can improve insulin sensitivity and blood glucose control, lower blood pressure, and reduce elevated blood fat, which all contribute to metabolic health.”
But how does that work? “An elevated waist circumference is associated with a change in the kinds of hormones and proteins the fat cells produce,” Dr Berry explains. “An increase in these causes a reduction in insulin sensitivity, releases lots of pro-inflammatory chemicals, and directly impacts type 2 diabetes risk, blood pressure and cholesterol.”
Measure your waist – accurately
You could have a Dexa scan to get an accurate measurement of your visceral fat. But taking your own waist circumference is adequate, if you do it properly, says Dr Berry. Find the midpoint between the top of your hip bone and the bottom of your ribs, or just use your belly button as a guide. Be consistent and measure at the same place each time for an accurate comparison.
According to the British Heart Foundation, for men, a waist circumference below 94cm (37in) is “low risk”, 94–102cm (37-40in) is “high risk”, and more than 102cm (40in) is “very high”. For women, below 80cm (31.5in) is low risk, 80-88cm (31.5-34.6in) is high risk, and more than 88cm (34.6in) is very high.
Make six eating changes that will help reduce your waist size
Your waist size is also influenced by genetics and by hormones.
“We know for example that men and women have different waist circumferences until middle age, but after menopause, women’s waistlines can increase and catch up.” But certain small measures can make a difference, says Dr Berry. “Set yourself up to succeed, firstly by not being tough on yourself and accepting that a wider waist can also be a natural part of ageing. Then take a few simple measures – ask yourself what you can do that’s easy with the biggest impact. After a month of doing one or two new things, add more. Take it slow and don’t rush the weight loss.”
