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In the dictionary, fast food is defined as any food which may be cooked easily, and is sold by restaurants to be eaten quickly or taken away. Changes in the dietary pattern of the last decades have made fast food a relevant component of Western diets, but a diet largely based on fast food has detrimental effects on health, which have been a matter of discussion for 20 years.1 Two potential mechanisms have been suggested: (1) fast feeding does not suppress appetite, leading to increased calorie consumption; and (2) fast food is usually richer in fats and saturated fats (and thus richer in calories), as well as in other components which may cause harm to several organs, namely widespread cardiovascular disease. Both mechanisms are likely to promote obesity, but is there evidence for a direct hepatotoxicity?
The issue came to public attention in the movie Super Size Me. After consuming three meals a day in a fast-food restaurant for 1 month, Morgan Spurlock increased by nearly 10 kg, and liver enzymes peaked at 290 U/l [alanine aminotransferase (ALT)] from baseline values of 20 U/l, accompanied by increased total cholesterol, uric acid and the onset of clinical features of the metabolic syndrome. There is no doubt that elevated aminotransferase levels are a marker of hepatic dysfunction, but are they related to any specific dietary component of fast food-based diet, or simply to weight gain and obesity-associated non-alcoholic fatty liver disease (NAFLD)?
EVIDENCE FROM EPIDEMIOLOGICAL AND CLINICAL STUDIES
In the general population, the majority of obese individuals do not have high liver enzymes. Also, in the presence of morbid obesity, more than half of individuals have liver enzymes within normal limits,2 although a significant correlation exists between the prevalence of abnormal liver enzymes and the degree of obesity. Accordingly, excess calorie intake cannot be the …
Competing interests: None.
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