Feasting on fast food triggers inflammation in the body, German researchers warn.
They say fat and sugar-laden, fibre-poor food, such as pizza, burgers and chips, can confuse the immune system, leading it to act as if it were fighting off an infection.
What’s more, the immune system remains on high-alert after eating these foods and will react even more aggressively to unhealthy foods in future, says Dr Eicke Latz, a researcher at the University of Bonn.
These findings, reported in the journal Cell in 2018, came from a study of mice, whose food was swopped for a "fast food" version. Latz believes the findings may be relevant to human health, helping to explain heart disease and type 2 diabetes, both of which are linked to poor diet and inflammation.
British experts say "ultra-processed food", containing artificial colourings, sweeteners or preservatives, can feed inflammation.
This would include soft drinks, ice-cream, biscuits, sugary cereals and chicken nuggets, as well as some low-fat spreads, protein bars and flavoured low-fat yoghurts.
Duane Mellor, a dietitian and a senior lecturer at Aston University Medical School, says this type of food can leave the body struggling to convert the extra calories cleanly into energy, generating high levels of free radicals - molecules thought to be involved in triggering inflammation.
He suggests thinking before you reach for a biscuit. If you’re bored, try making a cup of tea instead. And if you feel you can’t do without instant noodles, add some fresh or frozen vegetables. Besides being nutritious, they will help to cut your calorie intake.