Should your weight loss goal be a 'normal' weight?

In my practice, patients who I’m seeing for weight management will often tell me that they want to have a ‘normal’ weight. A google search of ‘normal weight’ will report back that a ‘normal’ body mass index (BMI) is 18.5-25.

While you can calculate your BMI here if you so choose, a goal of a ‘normal’ BMI or ‘normal’ weight is actually NOT recommended, because:

It is normal to carry elevated weight. In most countries, the majority of adults carry an elevated body weight. Only a minority of adults actually have a BMI 18.5-25. For this range of BMI, the term ‘healthy’ weight is better than ‘normal’. (though ‘healthy’ is not uniformly true, nor would I set this range as a target in any case – more on this below)

For a health care provider to set a ‘normal’ weight as a goal for their patient is actually very stigmatizing. My patients often tell me that they feel shame because other doctors have told them they are by definition ‘not normal’ . Remember: If you carry elevated weight, you ARE normal!

For the vast majority of people, it is not appropriate nor reasonable to target a BMI of <25. Genetics determine 40-70% of our body weight (and shape and fat distribution), and your genetics may just not allow your BMI to get that low. Also, most people with elevated weight have struggled for years, and over this time, the chronic inflammation associated with elevated weight causes scarring and damage to the appetite center of the brain, as well as other tissues in the body. As blogged previously, this elevates the set point of appetite to a higher weight, making it very difficult (to near impossible) to get a BMI down to <25.

BMI tells us nothing about body composition (muscle vs fat). There are many people who carry a BMI above 25 who have lots of muscle, little fat, and absolutely should not be targeting a BMI of <25. Also, the proportion and distribution of fat for a particular BMI varies by ethnicity. Some ethnicities (eg South/Southeast/East Asian) carry a higher proportion of body fat (and specifically the metabolically unhealthy visceral (central) fat) at a particular BMI than others. So, even if we relabel a BMI of 18.5-25 as ‘healthy’ instead of ‘normal’, there are still people who will have obesity inside this range, and people above this range who do not have obesity.

Some people will become sarcopenic (deplete in muscle) at a BMI <25. When we lose weight (by any modality), we lose about 2/3 of the weight as fat, and about 1/3 as muscle. At a BMI <25, many will retain a healthy amount of muscle mass, but others will not. Signs of sarcopenia include feeling weak, loss of strength, and there can be physical evidence as well. Older people are at higher risk of sarcopenia. (see this blog post for strategies to preserve muscle mass with weight loss)

Most importantly: We should not gauge weight management success solely on weight nor BMI. The primary target of weight management should be on improving health and quality of life. That being said, I appreciate that for many people (including many of my own patients), the numbers on the scale will always be an important target for them. If the numbers on the scale remain an important target for you, celebrate your weight management achievements alongside the improvements in health, with a goal in mind (discussed with your health care team) that is the Best Weight for you!

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