November 1, 2019

Weight Loss, Evidence Based Practice and the Role of the Fitness Professional

It is estimated to take 17 years for research evidence to reach clinical practice. In the case of fitness professionals and weight loss, two major things get in the way. One is the cultural assumptions we absorb about weight and weight loss, and one is that acknowledgement of what appears to be the futility of long term weight loss attempts may be perceived (incorrectly, in my view) as threatening the role and purpose of the fitness professional.

Let us start with a key finding of the research, evaluate our responsibilities in responding to this, and then consider the ways we can still promote improved health and wellbeing.

The Australian government’s health research body, the National Medical & Health Research Council (NHMRC) Level A evidence statement, which is based on eight metanalyses and represents the highest level of certainty, the same level of certainty of evidence we have that smoking causes cancer, states that:

  • Weight loss following lifestyle interventions is highest at 6-12 months
  • Regardless of the degree of initial weight loss, most weight is put back on within 2 years
  • By 5 years the majority of people will have returned to the weight they were at before they began the intervention(1).

Of course, a small percentage of people do maintain their weight loss beyond 5 years, but these people are statistical outliers and despite how often it happens without criticism, it would be both unethical and unscientific to represent these people’s experience as typical of what most people can expect from their weight loss attempts.

That weight is not as modifiable a risk factor as we might intuitively think or have been led to believe can be jarring, but if we are to be evidence based professionals, we simply must respect what the evidence tells us.

If we are going to provide assistance to a person in attempting weight loss, best practice requires that we communicate to them what the evidence suggests about the likelihood of achieving lasting weight loss, as well as some of the risks associated with weight loss attempts (development of eating disorders, weight cycling, increased body dissatisfaction, weight gain beyond pre-intervention weight(2)) so that they can provide informed consent.

The alternative is to provide advice about behaviours people can sustainably engage in to improve their health irrespective of changes to weight, size or shape – for example, enjoying a varied and nutritious diet, engaging in regular resistance and cardiovascular training activities, allowing adequate time for sleep and rest and fostering strong social connections and to support them to identify and implement meaningful change to these.

Fitness professionals are well placed to educate clients about the non-weight related health benefits of physical activity, including its effects on blood pressure, mood, bone density, cognition, memory, lung function, brain plasticity, joint health and all cause mortality and encourage them to focus on the variables that are under their control, acknowledging that health is complex and multi-factorial, and includes mental health. We can help clients set goals that are related to frequency of participation or performance outcomes or simply find ways to enjoy being active.

We can also educate ourselves about the negative impact that weight stigma has on health (both independently and due to barriers to accessing health services) and do our part to eradicate it in the environments we work in and the communities we are part of, which would in turn allow more people of all shapes and sizes to access fitness spaces and develop a positive relationship with exercise.

Fitness professionals have an important role to play in both education and facilitation, and can continue to focus on the positives of what the evidence tells us we can do to foster health and wellbeing.

Professional development in this area is available through

(1)  Health and Medical Research Council (2013) Clinical practice guidelines for the management of overweight and obesity in adults, adolescents and children in Australia. 
Melbourne: National Health and Medical Research Council, p69.

(2) Tylka, T., Annunziato, R., Burgard, D., Daníelsdóttir S., Shuman, E., Davis, C. and R Calogero. (2014) Weight-Inclusive versus Weight-Normative Approach to Health: Evaluating the Evidence for Prioritizing Well-Being over Weight Loss. Journal of Obesity 2014; Willer, F. (2014) Consent for Weight Management Strategy. Retrieved from