This article was written by Maeve Hanan (Registered Dietitian & Founder of Dietetically Speaking).

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Traditional health care models tend to be weight-normative or weight-centric. This encourages the pursuit of weight loss for those with bigger bodies, usually based on BMI ranges, with the aim of improving health and well-being. 

This might include routinely recommending trying to lose weight if somebody has a BMI over 25; possibly as part of the management of a health condition. 

But there are a number of problems with focusing on and emphasising the pursuit of weight loss. 

A note on language: This article refers to “overweight” and “obesity” at times when these categories have been used in research papers or within definitions by public health bodies. I have tried to minimise the use of these words elsewhere in the article, as I don’t use them on an individual basis as the definitions of these categories are flawed (as discussed below) and many people living in bigger bodies find these labels to be stigmatising. 

Issues With BMI

Body mass index (BMI) can be used as a rough snapshot of a person’s weight in relation to their height, but it often isn’t a good marker of individual health.

BMI has been found to be inaccurate as doesn’t give the full picture of body composition or take into account sex and race differences.

It also doesn’t scale well in terms of height, as a taller person with exactly the same body composition as a shorter person will have a higher BMI.

The BMI ranges are also very arbitrary and the upper limit for the ‘overweight’ category was controversially changed from 27.8 to 25 in 1998. You can read more about the strange history of BMI in this article by Your Fat Friend (Aubrey Gordon). 

Looking at population-based data (rather than as an individual health marker), current research suggests that those in the ‘overweight’ BMI category of 25-30 actually have the lowest risk of mortality and chronic disease (1). 

So all in all, BMI isn’t a helpful metric for many people to focus on.

Maintaining Weight Loss Is Often Not Realistic

There are so many factors that impact our health and weight, including our genetic blueprint and social factors such as having a lower income or education level. 

For example, economic struggles are associated with weight gain (2). When this is experienced in childhood this is also linked with a higher BMI in adulthood (3).  

Losing weight is also much more complex than eating fewer calories, in fact, dieting and restrictive eating are strongly linked with weight gain over time (4). 

As well as genetics and social factors, our body also has a number of biochemical processes that work to prevent weight loss. This includes reductions in metabolism and changes to hormones and chemical messengers that increase appetite (4-5).   

This is backed up by the lack of evidence that significant weight loss can be achieved and maintained by most people in the long run. A systematic review from 2017 found that only 43% of people who participate in weight loss studies can lose at least 5% of their body weight (6). Following on from that, research has found that the majority of people who intentionally lose weight regain this within five years, and roughly one to two thirds may gain more weight than they originally lost (7-10).

Weight loss studies also tend to have high dropout rates of 40-80% within the first year, which suggests that weight-loss diets may be unsustainable (11). 

The limited research that has resulted in more sustainable weight loss include an emphasis on health behaviours and behaviour change and have included a lot of intensive input (12-13).   

Weight Does Not Equal Health

There is much more to health than just weight or size. For example, a meta-analysis from 2014 found that those who were unfit had twice the risk of death regardless of BMI, whereas those who were fit and in the ‘overweight’ or ‘obese’ BMI categories had a similar mortality risk as those in the ‘healthy’ BMI range (14). 

A 2013 study found that metabolically healthy study participants in the ‘obese’ range had a higher risk of heart issues than metabolically healthy people in the ‘normal’ BMI range (1). But interestingly, for those who were deemed ‘metabolically unhealthy’ (i.e. they had a higher waist circumference, cholesterol, blood pressure or glucose levels) those in the ‘normal’ BMI range had a significantly higher risk of heart issues than those in the ‘overweight’ or ‘obese’ categories (1). 

Lots of health markers can also improve as a result of more movement, stress management or consuming more nutritious foods, even if weight doesn’t change (7-8).

This is an important point to highlight, as actively pursuing weight loss can be harmful to some people, and can actually reduce healthy behaviour due to lowered self-esteem, as it’s more difficult to take good care of ourselves well when we don’t feel capable or good about ourselves (7-8).

So in many cases focusing on health behaviours rather than weight is a safer and more appropriate approach. 

Losing weight can also be a red flag for many medical issues, and having a lower weight is linked with a number of health issues such as weakened bones, a poor immune system, fertility issues and worsened healing and recovery times. So the message that losing weight and being slim means automatic health is clearly oversimplified and wrong.   

Weight Stigma Plays a Big Role

Many studies don’t take into account the really significant impact that weight stigma can have on health.

A few different terms can be used related to size discrimination:

• Weight bias is defined as “negative attitudes towards, and beliefs about, others because of their weight. These negative attitudes are manifested by stereotypes and/or prejudice towards people with overweight and obesity.” (15). Weight bias can also be internalised by those living in bigger bodies. 
• Weight stigma is “actions against people with obesity that can cause exclusion and marginalization, and lead to inequities” (15). 
• Fatphobia is definaed as the “irrational fear of, aversion to, or discrimination against obesity or people with obesity” (16).  

Experiencing weight stigma has been linked with (17-19):

• Avoidance of healthcare settings
• Physiological stress in the body
• Inflammation
• Metabolic issues
• Depression
• Disordered eating
• A reduction in health behaviours

So it is thought that some of the health risks associated with being in a bigger body may be related to experiencing weight stigma. This article goes into more detail about weight stigma.

Pursuing Weight Loss Can Be Harmful

Trying to lose weight is associated with a higher risk of disordered eating, worsened body image, mental health issues, reduced health behaviours and weight cycling (7). 

Cycles of losing and regaining weight like this have been linked with an increased risk of (7, 20-22): 

• Mortality 
• High inflammation
• Raised blood pressure
• High cholesterol and heart disease
• Insulin resistance
• Gallstones
• Fractures
• Binge eating

It has also been suggested that weight cycling may account for the higher mortality risk in many studies, including the Framingham Heart Study, The Nurses Health Study II and the National Health and Nutrition Examination Survey (NHANES), rather than higher fat mass (7, 22). But ongoing research into the impact of weight cycling is needed. 

Trying to lose weight can be particularly harmful or triggering for those who have a history of disordered eating or a difficult relationship with food. Therefore, the pursuit of weight loss needs to be placed to one side during disordered eating recovery. 

Summary

Despite the strong focus that has existed in healthcare and society for years to strive for or maintain a smaller body, health is much more complicated than a number on the scales. 

To name a few important considerations, weight cycling, weight stigma, genetics and socioeconomic factors play a really significant role in health outcomes. The current evidence base demonstrates that maintaining weight loss is unrealistic for many people and there are a number of risks related to the pursuit of weight loss. 

For more information on this topic, check out this article about weight stigma and this article about weight-inclusive care.

References:

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