Summary Obesity prevalence rises fastest during young adulthood when weight, diet, and physical activity may be influenced by life events, including becoming a parent, but the impact is uncertain. We searched six electronic databases to July 2019 for longitudinal studies (both sexes) aged 15 to 35 years with a prospective pre‐pregnancy/parenthood and post‐delivery outcome. Of 11 studies (across 15 papers), six studies (women only) were eligible for meta‐analysis of the difference in change in body mass index (BMI; kg/m2) between remaining without children and becoming a parent. Mean (±SD) BMI gain for non‐mothers was 2.8 ± 1.3 kg/m2 (~7.5 kg for 164‐cm woman) over 5.6 ± 3.1 years; 12.3% of baseline BMI (22.8 ± 2.5 kg/m2). Becoming a mother was associated with an additional BMI increase of 0.47 ± 0.26 kg/m2 (~1.3 kg), 4.3% of baseline BMI (22.8 ± 5.6 kg/m2); the one study including men reported no difference in change. Physical activity results were equivocal; 2/4 studies (women) and 2/2 (men) showed a greater decline in parents versus non‐parents; diet (three studies) varied by dietary measure, mostly indicating no difference. Becoming a mother is associated with 17% greater absolute BMI gain than remaining childless. Motherhood BMI gain is additional to an alarming BMI increase among young women, highlighting the need for obesity prevention among all young women, including mothers.

Summary Early adulthood is a time when individuals go through important life transitions, such as moving from high school into higher education or employment, but the impact of these life transitions on changes in body weight, diet, and physical activity is not known. We searched six electronic databases to July 2019 for longitudinal observational studies providing data on adiposity, diet, and/or physical activity across education or employment transitions in young people aged between 15 and 35 years. We found 19 studies, of which 17 assessed changes in physical activity, three body weight, and five diet or eating behaviours. Meta‐analysis (n=9) found that leaving high school was associated with a decrease of −7.04 (95% CI, −11.26, −2.82) min/day of moderate‐to‐vigorous physical activity. Three studies reported increases in body weight on leaving high school. A small number of studies suggested decreases in diet quality on leaving high school (n=2/4 papers) and leaving university (n=1) but not on starting employment (n=1). Studies suggested no change in physical activity on leaving university (n=4) but decreases in physical activity on starting employment (n=2/3). The transition of leaving high school is an important time to support individuals to prevent decreases in physical activity and gains in body weight.

BackgroundDespite inconclusive evidence, the idea that a lack of home food preparation and skills is a limiting factor in achieving a healthy diet is widespread. Cooking skills interventions proliferate, and several countries now mention cooking in their dietary guidelines. The aim of this study was to determine whether substantial consumption of home-prepared food is necessary for high dietary quality by exploring whether individuals can eat healthily while eating little home-prepared food. The diets of these individuals were characterised, and socio-demographic characteristics and prevalence of obesity were also explored.MethodsCross-sectional analysis of UK dietary survey data with objectively measured height and weight and a 4-day food diary for each participant was conducted. A subsample (N = 1063, aged ≥19 years) with a high dietary quality (determined using a score derived from the Dietary Approaches to Stopping Hypertension (DASH) diet) was analysed. Within this, participants were grouped as either high or low home preparation based on the proportion of energy derived from home-prepared food. Regression models were used to determine whether and how those in the high and low home preparation groups differed in terms of socio-demographic characteristics, DASH score, energy intake, prevalence of obesity, and dietary composition.ResultsThe low home preparation group included 442 participants, while 621 participants were in the high home preparation group. The low home preparation group were more likely to be older and white, and less likely to have a degree level education. After adjustment for socio-demographic characteristics, there were no differences in DASH score, energy intake or obesity prevalence between the groups. After adjustment, the low home preparation group consumed more fruit (30.8 additional g/day, 95% CI 5.5–56.1), more low-fat dairy foods (24.6 additional g/day, 95% CI 1.7–47.5) and less red meat (10.4 fewer g/day, 95% CI 4.3–16.6), but also more sugar (11.6 additional g/day, 95% CI 7.5–15.6) and sodium (107.8 additional mg/day, 95% CI 13.8–201.8).ConclusionHome food preparation should not be presented as a prerequisite to a high quality diet. The public health community should recognise the existence of a set of food practices which allows individuals to achieve a healthy diet with little contribution from home-prepared food, and make space for it in the design of their policies and interventions.