Slimming down does a fat lot of good if your metabolism is off-kilter

A big waist is never a good sign but a lack of obesity doesn’t guarantee good health.

Good metabolic health is associated with physical activity.

We’re so bombarded with mes­sages about weight that we tend to think it’s all that matters, and that as long as weight gained is subsequently lost we’ll be as healthy as we were before. That ignores what we’re doing to our systems when we deliberately overload them with fat, sugar, alcohol, calories, chemicals and processed food.

We can see weight gain but we can’t see what else is going on underneath the skin, to our blood pressure, the fat circulating in our bloodstream, our capacity to deal with excess sugar, the silent narrowing of our arteries as they get furred up. These factors measure our metabolic health, the invisible delicate mechanisms that keep us healthy and alive. Until they don’t, killing or incapacitating us from strokes or heart disease, diabetes or heart attacks.

Last year, researchers from the University of North Carolina who have been tracking data for almost 9000 American adults across seven years discovered that only 12 per cent of the population is metabolically healthy. It means that even people who aren’t yet overweight or obese are wreaking great damage on themselves.

This study found that fewer than a third of normal-weight adults and fewer than half of underweight adults are metabolically healthy. The wrong diets and lifestyles are undermining even those people who look as if they’re perfectly fine. Assuming that obesity is all we need worry about is a dangerous mistake. Endocrinologist Rekha Kumar says: “Even people who are a normal weight seem to be developing diseases that we typically correlate with obesity.”

Our bodies could shrug off a day of excess if it was against a background of general restraint, but that’s not how we live now. After Christmas festivities, we think we can erase all the cumulative damage by going to the gym in January and drinking lots of green juice. That’s an error.

The effect is as if we took a car out into a bumpy field, careered around at full speed, ran out of oil and water, jolted and damaged the chassis, filled it with contaminated fuel, seized up the engine, then thought that some new fuel and a paint job would mean it was as good as before. The emerging evidence is that our bodies need much more complex care than just avoiding excess calories.

Obesity is only one of the factors we need to think about. It is possible, although not usual, for obese people to avoid metabolic ill-health. Up to 30 per cent of them do, although they are at greater risk than normal-weight people of developing it in the future. In a four-year study of almost 7000 adults in South Korea, the non-obese subjects who were metabolically unhealthy (with more than one of the following conditions: high blood pressure, impaired insulin control, high blood glucose, high triglycerides or low levels of good cholesterol) were three times likelier to develop diabetes than those subjects who were obese but metabolically fine.

Similarly, a 2017 study of overweight British men found that individuals with a poor metabolic score were three times likelier to die than those with good metabolic health, regardless of how fat they were. This raises the question for all of us: how do we diagnose and protect ourselves? Where do we draw the line between happy occasional feasting and dangerous indulgence?

GPs can run tests for metabolic measurements, but the simplest visible sign of metabolic malfunctioning is a very large waist. Body fat matters less. Even people who are overweight can be fit if they are active and avoid rubbish food. Good metabolic health is strongly associated with high levels of physical activity, quitting smoking, eating vegetables and fruit, leaving four-hour gaps between meals or snacks, and minimising sugar splurges, alcohol overload and anything our great-grandmothers would not have eaten.

The Times