Lost your exercise motivation lately? It might not be your willpower alone that’s to blame. An alarming new piece of American research has revealed a strong link between a common food additive and a lack of physical activity.

In America, where the research took place, only a third of people manage the recommended amount of exercise each week. But there’s now evidence linking this sedentary behaviour with inorganic phosphate, according to scientists at the University of Texas Southwestern Medical Center in Dallas.

The substance is often present in processed foods including meat such as ham, sausages and canned fish as well as fizzy drinks. Researchers estimate that around a quarter of adults in the US regularly consumer between three and four times more phosphate than recommended.

The initial study was carried out on mice, with half on a normal, healthy diet, and half receiving extra phosphate (in proportion to the amount that US adults consume). Over the course of 12 weeks, there was a correlation between the phosphate mice spending less time exercise and having lower levels of cardiac fitness. Not only that, but the added phosphate also impaired their metabolism and slowed down their ability to burn fat.

A second study was carried out on 1,600 healthy people wearing fitness trackers. Again, added phosphate resulted in less activity.

Normally your kidneys can control the phosphate levels in your blood, with any excess filtered out when you urinate. But these unnatural levels of added phosphate can be a challenge, particularly for impaired kidneys. Previous studies have shown a link between mortality rates and excessive phosphate levels in people with kidney disease.