Childhood stress fuels weight gain, and why we find French fries irresistible

Women who experience higher levels of childhood stress gain weight more rapidly than those who have less childhood stress, finds a new US national study led by Michigan State University. With men, however, neither childhood nor adult stress was associated with weight gain. Hui Liu, an associate professor of sociology, headed the study that involved 3,617 men and women interviewed four times over a 15-year-period. Childhood stress was measured on a range of family-related stressors that occurred at age 16 or younger, such as economic hardship, divorce, at least one parent with mental health problems and never knowing one's father. Adult stress included such factors as job loss, death of a significant other and parental and care-provider stress. Liu says gender differences in responses to stress as well as depression could explain the different findings between men and women. The study highlights the need for treatment and policies designed to reduce stress in childhood, the researchers say.

Find those French fries irresistible? A new study uncovers why: in tests on rats, a high-fat diet changes the populations of bacteria residing inside the gut and also alters the brain's ability to recognise fullness, which can lead to overeating. "The brain is changed by eating unbalanced foods. It induces inflammation in the brain regions responsible for feeding behaviour. Those reorganised circuits and inflammation may alter satiety signalling," says Dr Krzysztof Czaja, the study's principal investigator, who is an associate professor of neuroanatomy at the University of Georgia's College of Veterinary Medicine. The effect of a high-fat diet in rats was "immediate", he says, and introduced a "significant change" in the gut microenvironment that "triggers a cascade of events". Czaja and his team plan to investigate if this change is permanent or reversible. The study was presented last week at the annual meeting of the Society for the Study of Ingestive Behaviour.

Vulnerability to heart disease is the main reason men don't live as long as women, according to a new study led by the University of Southern California. Significant differences in life expectancies between the sexes first emerged at the turn of the 20th century. As infectious disease prevention, improved diets and other positive health behaviours were adopted by people born during the 1800s and early 1900s, death rates plummeted, but women began reaping the longevity benefits at a much faster rate. The study examined the lifespans of people born between 1800 and 1935 in 13 developed nations. Focusing on mortality in adults over 40 years of age, the team found that in individuals born after 1880, female death rates decreased 70 per cent faster than those of males. Even after controlling for smoking-related illnesses, cardiovascular disease appeared to still be the cause of the vast majority of excess deaths in adult men over 40 for the same time period. The uneven impact of cardiovascular illness-related deaths on men raises the question of whether men and women face different heart disease risks due to inherent biological risks and/or protective factors at different points in their lives.