Opinion: research shows that engaging in physical activity in response to food choices may do more harm than good

A recent study outlined that "physical activity calorie equivalent" on food labelling may "reduce the number calories selected from menus and decrease the number of calories/grams of food consumed by the public", and thus be one effective antidote to the obesity crisis. The central claim of these labels is that understanding how much physical activity is needed to 'burn' it off will make you think again when you go to buy your favourite chocolate bar.

The research has received much traction and controversy online and in mainstream media. While the findings were initially welcomed by the Royal Society for Public Health, they have been criticised by many leading academics and charities including Parkrun. This message risks compounding population trends of declining physical activity and overlooks the wider potential mental, social and physical health benefits of being active.

One may have multiple and sometimes conflicting motives for being active and these can ebb and flow. A classic example is the influx of January gym memberships for New Year's resolutions. In many, if not most, cases, gym memberships receive poor attendance, and cancellations involve major expense to consumers.

From RTÉ Radio 1's News At One, Niall Moyna from DCU on taking on realistic goals for exercise and weight loss

Decades of behavioural science research show that autonomous motives, such as being active for personal enjoyment or for health, are likely to result in continuation of the activity over time. In contrast, being active for introjected or external reasons, such as shame or guilt towards one’s diet or body image, is highly unlikely to be maintained over a continued time.

Despite the potency of introjected punishments for changing one’s behaviour, they are typically short-lived, and linked with poorer mental health. As such, physical activity to compensate for one’s calorie consumption risks physical activity being framed as a punishment or deterrent for unhealthy lifestyles, which ironically is unhealthy in itself. 

The psychology of exercising for such potentially harmful reasons may be exacerbated in labelling which would largely equate physical activity with its caloric burning properties, and overlook a myriad of potential health benefits. Indeed, research shows that exercise practitioners who develop exhausting but time-efficient "get fit quick" and "fat burning" routines for their clients often produce physical activity experiences which are unpleasant and enduring. This view is articulated well by Panteleimon Ekkekakis, who has shown that adults’ early negative memories of Physical Education are a significant factor in their present sedentary lifestyles.

From RTÉ Radio 1's Today with Sean O'Rourke, chartered physiotherapist Jenny Branigan and Niall Moyna from DCU discuss age-appropriate exercise

Promoting the positive social, physical and mental health benefits of physical activity is more effective and supported in research across Ireland, which shows that meeting the WHO's physical activity guidelines is associated with improved health. The Sport for LIFE: All-Island team led by Professor Deirdre Brennan and Dr. Gavin Breslin surveyed over 700 children and found positive mental health, social belongingness and healthy body composition among active children compared to inactive children.

A further school-based programme, led by the author, found that mental health was enhanced by physical activities that children enjoyed, felt socially supported in, and experienced personal competence. Additionally, the Student Activity and Sport Study Ireland led by Professor Marie Murphy surveyed over 8,000 students over the age of 18 and showed that those meeting the aerobic physical activity guidelines reported greater general health and mental health compared with inactive peers.

Despite the positive links with physical activity and health, just under 57% of children and 41% of adults currently meet WHO guidelines in Ireland

Subsequent findings have shown that these mental health benefits are further improved when the individual engages in muscle-strengthening exercises such as weight-training or Pilates) alongside aerobic activities. Despite the positive links with physical activity and health in our data, we estimate that just under 57% of children, and 41% of adults currently meet WHO guidelines in Ireland. Furthermore, a 12-week programme in an all-island trial was not able to significantly alter children’s weekly physical activity.

What these findings highlight is that behaviour change is difficult to achieve, and health-promoting physical activity requires consideration of various social and psychological factors. To this end, the inference is that engaging in physical activity in response to food choices may do more harm than good. While there is no "one-size fits all" approach to behaviour change, current evidence clearly highlights the risks and negative implications of using physical activity as a deterrent, or punishment to food choices. Rather, physical activities that satisfy our psychological needs and improve our mental health are important for feeling self-determined in our behaviour change, and are much more successful.

This view is supported in our research, highlighted by leading psychological theorist, Richard Ryan, and categorised into three areas. 

- Competence: aim for activities that provide a challenge, but are also within your capability. Whether this means you begin taking the stairs instead of the lift, walking for 10 minutes per-day, or climbing a mountain once a month, you will feel a sense of accomplishment, and progress these activities in future.

- Autonomy: consider the degree of choice and how self-determined you feel for specific physical activities. Choosing those that you enjoy and fit within your lifestyle can go a long way.

- Social belongingness: being active offers an opportunity to gel with friends and family, or meet new people. A range of activities including recreational five-aside football, Parkrun or walking/hiking clubs offer this possibility. 

If you're considering your physical activity levels, think about what gives you satisfaction and what’s achievable over the long term. Resolve to make a change of lifestyle, rather than listen to how food labelling would wrongly frame physical activity as a calorie-burning antidote to the obesity crisis


The views expressed here are those of the author and do not represent or reflect the views of RTÉ