Eating too many burgers, pizzas, biscuits and cakes can knock years off your life, according to new research.
A study of almost 45,000 middle-aged people found that deaths from heart disease, cancer and other illnesses were linked to the consumption of 'ultra-processed food'.
These include: chips, white bread, ready meals, sausages, sugary cereals and fizzy drinks - essentially any product involving an industrial procedure.
Worryingly, these snacks make up half the average Briton's diet, which is prematurely killing us, say scientists.
Fact: In addition to higher contents of total fat, saturated fat and added sugar, many fast food items contain legal but controversial additives such as sodium nitrite and titanium oxide
Previous research has shown that these fat-rich, low-fibre foods cause high blood pressure and cancer, but this is the first to investigate consumption and mortality risk.
Co-author Dr Laure Schnabel, a nutritional epidemiologist at Paris-Sorbonne University, said: 'Ultra-processed foods contain multiple ingredients.
'The nutritional characteristics of [these] could partly explain the development of non-communicable chronic diseases among those who consume them.'
In addition to having a higher content of total fat, saturated fat and added sugar, many fast food items contain legal but controversial additives such as sodium nitrite and titanium oxide.
Meanwhile, artificial sweeteners - which are also commonly present in snacks - are suspected of altering gut bacteria, which increases the risk of type 2 diabetes and other metabolic diseases which are major causes of premature mortality.
Likewise, food packaging is suspected to have hormone disrupting chemicals, some of which might cause cancer, diabetes and obesity - such as bisphenol A.
Together, when consumed in substantial volume over time, they can trigger long-term, potentially fatal illnesses.
Too much: Last year, a study of 19 European countries found 50 per cent of food sold in the UK is ultra-processed compared with 46 per cent in Germany and 14 per cent in France
The findings, published in JAMA Internal Medicine, were based on a survey of 44,551 healthy 45-to-64-year-olds in France, with an average age of 57 who kept 24-hour dietary records.
This enabled researchers to measure their intake of more than 3,000 different food items classified into four groups depending on their level of processing.
Overall, fast food accounted for 29 per cent of total energy intake - about 20 per