How much physical activity is needed for weight loss, weight loss maintenance, and weight gain prevention?

High physical activity levels (PAL) or exercise training (ET) should be an integral part of any treatment plan for individuals regardless of weight loss goals and is associated with numerous CV benefits (Haskell et al., 2007)

A question often encountered in my office is how much exercise is needed to lose weight and what type of ET should be performed. The present American College of Sports Medicine (ACSM) recommends physical activity to maintain health (Haskell et al., 2007) and promote weight loss (Donelly et al., 2009).

Physical activity and the prevention of weight gain

Evidence from the CARDIA study demonstrates a weight gain of approximately 0.5–1 kg annually in adults (Dutton et al., 2006). How do we attenuate that? The evidence for a volume threshold of physical activity associated with preventing weight gain in adults appears inconsistent. As noted above, the ACSM position stand recommends 150-250 minutes per week of moderate to vigorous PAL, with an energy equivalent of 1,200 to 2,000 kcal per week (Donelly et al., 2009). Others suggest 10,000 steps per day to prevent increases in BMI. Jakicic et al.'s (2019) literature review supports more significant amounts of physical activity to prevent or minimize weight gain, noting a dose-response relationship, with the prevention of weight gain more pronounced when moderate-to-vigorous intensity physical activity (>3 METS) is above 150 min/week.

Lee et al.'s (2010) prospective cohort study (n=34,079 healthy US women, mean age, 54.2 years) observed that the risk of weight gain over three years was 11% greater in women who participated in less than 7.5 metabolic equivalent MET hr/wk compared to women who participated in greater than 21 MET hr/wk.

The Institute of Medicine suggests that 60 minutes a day (420 minutes per week) of moderate-intensity activity may be needed to prevent individuals from developing overweight or obesity. These recommendations are based on the training required to raise an individual from the passive to the active PAL category, with higher-intensity activities requiring less time.

Weight loss from specific exercise programs for patients with overweight or obesity

Swift et al. (2014) review notes that unless the overall volume of aerobic ET is very high, clinically significant weight loss is unlikely to occur. This is important clinically as many patients present to the clinic and note that they have started exercising (often not changed anything else) and haven't indicated any weight loss. The most commonly reported is the addition of walking. Walking alone has not consistently been associated with a weight or BMI change or the incidence of developing obesity (Caudwell et al., 2009). This is often a misconception and can impact patient morale and progress if not discussed. We should, therefore, caution patients that the chances of substantial weight loss are unlikely at these ET levels without additional caloric restriction.

Exercise programs need to exceed 225 min/per week, according to ACSM, to induce clinically significant weight loss (Donelly et al., 2009). Ross et al. (2000) noted an 8% weight loss, particularly abdominal obesity and insulin resistance, in men with obesity after 12 weeks of aerobic ET with no alterations in dietary habits. The total fat decrease was noted with an 'average reduction was 1.3 kg (95% CI, 0.3 to 2.3 kg) greater in the exercise-induced weight loss group than in the diet-induced weight loss group (P = 0.03)'.

There is a dose-response relationship between physical activity and health. It is, therefore, noteworthy that to improve their fitness further, reduce their risk for chronic diseases and disabilities, or prevent unhealthy weight gain, all patients may benefit from a PA conversation and encouragement to meet but exceed the minimum recommended amounts of physical activity. (Haskell et al, 2007).

Weight Maintenance and Prevention of Regain

Et al. has a vital role in weight regain after initial weight loss. Reviewing the figure above shows that a higher recommendation exists to prevent weight regain after loss than for initial weight gain. Again, this is important clinically, with long-term exercise goals required as part of the patient maintenance plan. Jakicic et al. (2003) note after 12 months of intervention, women with greater than 200 min/week (13.6%) had maintained a significantly more significant percentage of weight loss compared to those who had exercised at 150-199 min/week (9.5%), and less than 150 min/week (4.7%)'.

As we note above, exercise discussions have a role in the exam as we discuss the prevention of obesity, develop weight loss plans, and help with weight maintenance. As a guide, I am now utilizing an exercise prescription as part of my four-pillar approach and using OMA's online resources.