In a meta-analysis of real-life experiments drawn from food science, nutrition, health economics, marketing and psychology, the authors find that behavioural nudges - facilitating action rather than providing knowledge or inducing feelings - can reduce daily energy intake by up to 209 kcal, the same number of calories as in 21 cubes of sugar.

“Tracking your daily activity with a pedometer, wearable, or smartphone is an important part of any physical activity program,” Patel said by email. “However, it should be combined with other behavior change strategies such as goal-setting, coaching, or social interventions to increase sustainability.”

If you want a child to eat more vegetables, it might help to use plates illustrated with pictures of vegetables.

Gamification offers advantages over other types of physical activity campaigns due to its ability to bypass the perceived barriers to becoming active. Gamified design can deliver health through stealth by encouraging people to play a fun, free game rather than take part in a fitness scheme.

Strategies for Enhancing Health in the Built Environment

Mental contrasting is essentially contrasting your happy, dream goal with your current reality, emphasizing the need for action, while implementation intentions are "if-then" statements about how you will deal with obstacles. The link goes to a journal article in which this combined technique was used to help women become more physically active, and the effect was sustained over months.