Why you can’t judge health by weight alone

Rachel Woods, University of Lincoln

How much does your weight really say about your health? Probably less than you think. You could eat your five-a-day, hit the gym regularly, have textbook blood pressure and cholesterol levels – and still be dismissed as “unhealthy” based on the number on the scale. Meanwhile, someone with a so-called “healthy” weight might be skipping meals, running on stress and caffeine, and rarely moving their body.

We’ve been taught to equate thinness with wellness and excess weight with illness. But the science tells a more nuanced story – one where weight is just a single data point in a far more complex picture. So if weight alone doesn’t reflect how healthy we really are, what does?

Body weight is one of the most measured aspects of health. Society places huge emphasis on it, and criticism of a person’s weight is often framed as a health concern. So how much meaningful health information does weight actually offer?

Simply put, body weight measures exactly that – the total weight of a body. Changes in weight over time can give an indication of a person’s calorie intake. If they are gaining weight, they are eating more calories than they burn. If they are losing weight, they are burning more than they eat.

It is perhaps more useful to consider the health information weight doesn’t give us. Important health indicators, such as cholesterol, blood sugar, blood pressure and heart rate are not visible on the scales.

Neither does weight reflect the quality of someone’s diet. A person could be eating plenty of fruit, vegetables and whole foods, getting the vitamins and minerals needed for good energy, bone strength and immune function. Or they might not. They might be eating mostly healthy fats, like those found in olive oil, nuts and fish, which are linked to better heart health. Or they may get their fat from processed foods, high in saturated and trans fats, which increase the risk of heart disease. They may be getting plenty of fibre to support digestion, regulate their blood sugar and maintain healthy cholesterol, or they may be getting very little. Weight alone reveals none of these important dietary details. https://www.youtube.com/embed/B9zhrxeYKYA?wmode=transparent&start=0

Weight also doesn’t accurately reflect how much body fat someone carries, or more importantly, where that fat is located. Visceral fat (which surrounds the internal organs) is linked to a higher risk of heart disease, type 2 diabetes and some types of cancer, whereas subcutaneous fat, found just beneath the skin, poses fewer health risks