Background: To date, no physical activity (PA) questionnaires intended for primary care have been compared against a criterion measure of PA and current (2008) aerobic PA recommendations of the American College of Sports Medicine/American Heart Association (ACSM/AHA). Aim: This study evaluated preliminary evidence for criterion validity of two brief (<1 min) PA questionnaires with accelerometry, and their ability to identify if individuals meet ACSM/AHA PA recommendations. Methods: 45 health clinic staff wore an accelerometer for seven consecutive days and afterwards completed two brief PA questionnaires, the Physical Activity Vital Sign (PAVS), and the Speedy Nutrition and Physical Activity Assessment (SNAP). Agreement and descriptive statistics were calculated between the PAVS or SNAP and accelerometry in order to measure each questionnaire’s ability to quantify the number of days participants achieved ⩾30 min of moderate–vigorous PA (MVPA) performed in bouts of ⩾10 continuous minutes. Participants with <5 days of ⩾30 bout-min of MVPA were considered insufficiently active according to PA recommendations. Findings: There was a significant positive correlation between number of days with ⩾30 bout-min MVPA and the PAVS (r=0.52, P<0.001), and SNAP (r=0.31, P<0.05). The PAVS had moderate agreement with accelerometry for identifying if individuals met or did not meet PA recommendations (κ=0.46, P<0.001), whereas SNAP had poor agreement (κ=0.12, P<0.05). Conclusions: This study provides preliminary evidence of criterion validity of the PAVS and SNAP with accelerometry and agreement identifying if respondents meet current (2008) ACSM/AHA aerobic PA recommendations. The PAVS and SNAP should be evaluated further for repeatability, and in populations varying in PA levels, age, gender, and ethnicity.

Treatments to induce weight loss for the obese patient centre on the achievement of negative energy balance. This objective can theoretically be attained by interventions designed to achieve a reduction in energy intake and/or an increase in energy expenditure. Such ‘lifestyle interventions’ usually comprise one or more of the following strategies: dietary modification; behaviour change; increases in physical activity. These interventions are advocated as first treatment steps in algorithms recommended by current clinical obesity guidelines. Medication and surgical treatments are potentially available to those unable to implement ‘lifestyle interventions’ effectively by achieving losses of between 5 kg and 10 kg. It is accepted that the minimum of 5% weight loss is required to achieve clinically-meaningful benefits. Dietary treatments differ widely. Successful weight loss is most often associated with quantification of energy intake rather than macronutrient composition. Most dietary intervention studies secure a weight loss of between 5 kg and 10 kg after intervention for 6 months, with gradual weight regain at 1 year where weight changes are 3–4 kg below the starting weight. Some dietary interventions when evaluated at 2 and 4 years post intervention report the effects of weight maintenance rather than weight loss. Specific anti-obesity medications are effective adjuncts to weight loss, in most cases doubling the weight loss of those given dietary advice only. Greater physical activity alone increases energy expenditure by insufficient amounts to facilitate clinically-important weight losses, but is useful for weight maintenance. Weight losses of between half and three-quarters of excess body weight are seen at 10 years post intervention with bariatric surgery, making this arguably the most effective weight-loss treatment.

Obesity, physical activity status and circulating levels of sex steroid hormones and growth factor proteins are intrinsically linked to energy balance. Epidemiological studies have previously reported associations between these factors and the risk of hormone-related cancers such as prostate and breast cancer in men and postmenopausal women. An increasing number of intervention studies in ‘at-risk’ populations and cancer survivors are now investigating the effects of lifestyle interventions that promote negative energy balance on circulating levels of sex hormones and growth factor proteins as surrogate markers of cancer risk. Evidence from these studies suggests that lifestyle interventions can improve insulin sensitivity, alter the balance of circulating sex steroid hormones and insulin-like growth factor (IGF) axis proteins (including IGF-1 and the IGF binding proteins 1 and 3) and change the functioning of immune cells in peripheral blood. Such changes could influence the risk of developing hormone-related cancers, as well as having the potential to improve disease-free survival in patients recovering from cancer treatment. However, despite promising results, the methodological quality of most intervention studies has been limited due to small subject numbers, lack of adequate control groups or non-randomised designs and the absence of long-term follow-up measures. More intervention studies with randomised controlled designs, higher numbers of subjects and longer-term follow-up measures are needed to establish which combination of specific dietary and physical activity interventions work best for reducing risk in ‘at-risk’ populations and survivors, optimal dose–response relationships and the magnitude of change in surrogate markers of cancer risk that is required to induce a protective effect.