“Healthy weight” can be a charged term. Here’s what you need to know about the relationship between health and weight, how body weight is measured and what to consider as you make decisions that are best for you and your body.
What is a healthy body weight?
This deceptively straightforward question is sticky because the answer depends on how you define health.
“Weight is objective, but a ‘healthy’ weight is not so clear cut. It requires one to define what being healthy is, which can vary from person to person,” says Kristi Peterson, a dietitian nutritionist who works at multiple UW Medicine Primary Care clinics.
To Peterson, a healthy weight could be defined as a weight at which you are in sound mind, body and spirit that you can reasonably maintain while engaging in generally healthful behaviors.
“Weight doesn’t tell me what someone is doing with their body, how they are moving it and other things that constitute health. I think it’s cheap and doesn’t show much,” she says.
Still, the concept of a healthy weight is prevalent in medicine and society, and there are tools doctors use to determine if your weight puts you at a higher risk of disease.
How is healthy weight determined?
Doctors currently use two main screening tools to determine if your weight puts you at higher risk of disease: body mass index (BMI) and waist circumference.
Body mass index (BMI)
If you’ve been to the doctor recently, they’ve probably measured your height and weight, which are used to determine your BMI.
Your body mass index is your weight in kilograms divided by the square of your height in meters. Your results put you in one of four categories: underweight (a BMI less than 18.5), healthy weight (18.5-24.9), overweight (25-29.9) and obese (30-plus).
BMI is used because it is inexpensive and easy to calculate. However, it’s also flawed.
“As we have learned about obesity, we are also learning more about how BMI is not the best way to measure health and body fat. BMI can be inaccurate in athletes with more muscle mass, older people with less muscle mass and different ethnicities,” says Dr. Laura Montour, an obesity medicine expert at the UW Medical Center – Roosevelt Center for Weight Loss and Metabolic Surgery.
This is because BMI doesn’t differentiate between what is contributing to your weight (muscle mass, internal organs and so on), meaning, for example, athletes with a lot of muscle can have a BMI in the obese category.
Moreover, BMI was not created by doctors to determine individual medical health. Instead, it was created by a mathematician in the 1800s who studied white, European men to assess the size of an average man. (So, yeah. Not exactly the ideal way to determine health for women, people of color, or even health risks of individual white men).
Nonetheless, because BMI is a cheap and easy way to measure body weight — and because it can show trends on a population level — it is often used in medical research to show correlation (though not causation) between weight and future health risks.
Waist circumference, the other screening tool, can be used in addition to BMI to provide a clearer picture of health.
A higher waist circumference is correlated with increased body fat around the abdominal organs, which in turn leads to obesity-related conditions like Type 2 diabetes, coronary artery disease and high blood pressure, Montour says.
Waist circumference is measured with a tape measure just above your hip bones and taken after you’ve exhaled. Nonpregnant women with a waist circumference of more than 35 inches and men with a waist circumference of more than 40 inches are at higher risk of developing obesity-related conditions.
What about the good old-fashioned bathroom scale, you ask?
It can be helpful to note changes in weight or to monitor weight, but it does not tell you if you are healthy or not. Plus, in a test by Consumer Reports, all six scales tested failed to accurately measure body fat percentage.
The bottom line on measuring weight: “To fully assess health, people should see their primary care provider to have height, weight, waist circumference, blood pressure and laboratory tests,” Montour says.
What factors affect your weight?
A variety of factors can influence your weight, including:
- Food access and eating habits
- Physical activity
- Certain diseases or conditions
- Digestion and absorption of nutrients
“Let’s say someone is experiencing an increase in work related stress. That in turn may be disrupting sleep which may then alter appetite and therefore, weight,” Peterson says.
In other words, your weight isn’t determined by your willpower to stick to a particular diet or exercise regimen. While exercise and food play a role, they are only a part of what determines your weight.
How does your weight affect your physical health?
Peterson, Montour and Halter agree that weight on its own cannot determine health. But there is a correlation between health and weight.
Research studies have indicated excess weight from body fat increases your risk of:
- Type 2 diabetes
- Heart attacks and stroke
- Depression and anxiety
- Premature death
Being underweight and undernourished can also lead to chronic conditions such as:
- A depressed immune system
Weight cycling is bad for your health
In addition, weight cycling, or losing and then regaining weight, can harm your metabolism and increase your disease risk. Note that this refers to repeated weight loss and gain often caused by restrictive dieting, not the slight fluctuations in weight throughout your day or week (which are normal).
“What weight loss studies often overlook is if you lose weight, you may see changes to health markers, but almost inevitably if you follow those folks out, they will regain the weight and may end up with worse health markers because the weight cycling causes its own health problems,” says Dr. Megan Riddle, a psychiatrist who specializes in eating disorders and a courtesy faculty member in the Psychiatry and Behavioral Sciences Department at the UW School of Medicine.
In sum, weight does factor into health, but you can’t determine disease risk just by looking at your (or someone else’s) weight or size. This is why it helps to talk with your doctor about what is best for you — whether that means adjusting your weight or not, and how to do so in a way that is sustainable.
How does your weight affect mental health (and vice versa)?
Weight and mental health have a bidirectional relationship, meaning each one affects the other.
Mental health conditions like chronic stress, anxiety and depression can influence your appetite and cravings, making it harder to maintain weight. On the flip side, if you are heavily restricting, this can lead to fatigue, difficulty concentrating, loss of interest and poor sleep, mimicking symptoms of depression.
Diet culture and weight stigma can also lead to shame, self-criticism and disordered eating, Riddle says.
“We know restrictive dieting promotes weight cycling and disordered eating and can affect body image and your sense of self,” she says. “There are a lot of fallouts in physical and mental symptoms.”
Can you be healthy at every size?
There is ongoing debate in the medical community about if you can be healthy at every size.
The Health at Every Size (HAES) movement is an approach to health that prioritizes overall well-being instead of weight and encourages body acceptance, intuitive eating and enjoyable physical activity.
“A lot of times in medicine, we start the discussion from the lens of weight. The Health at Every Size philosophy starts the conversation with your health, preventive actions you can take and concerns you have,” Halter says.
Research on the HAES approach is limited by small sample sizes and a focus on white women with a history of binge eating or chronic dieting. Still, studies have shown HAES interventions can lead to improvements in psychological well-being (self-esteem, body image and mental health) and metabolic health (blood pressure and lipids).
One reason some doctors push back against the idea of health at every size is that metabolic health (what was shown in the HAES studies) doesn’t always result in a reduced risk of disease, Montour says. There is research indicating that even if you are obese and do not have metabolic complications related to excess weight, you can still have higher risk of cardiovascular disease and cancer.
What is indisputable — and what Halter and Montour both emphasize — is that weight stigma and bias are harmful for everyone, especially the weight stigma that exists within the medical community. Again, there isn’t one shape or size of body that equates to health. What is healthy may look different from person to person, so you cannot look at someone’s body and determine their health (and making these determinations is, frankly, rude).
What can you do to lose, gain or manage weight in a healthy way?
Whether you are looking to gain or lose weight, leaning on support — including medical professionals like dietitians and experts in metabolic diseases — is crucial. These experts can help with behavioral support, mental health, medication and, in some cases, bariatric surgery.
“It’s cliché, but we cannot escape the fact that everyone is different and comes to the journey of gaining or losing weight with different experiences that will influence how we approach reaching their goals,” Peterson says.
Along with talking to your doctor, she and the other UW Medicine experts recommend these tips for managing weight in a way that is physically and mentally healthy.
Consider what is sustainable and enjoyable
Set yourself up for success by making a plan that works for you.
In other words, if you want to lose weight but hate running, don’t create a plan that revolves around jogging before work every morning. If you love chocolate, don’t force yourself to give it up.
“Cutting out something you love is usually temporary,” Peterson says. “It’s worth your time to figure out how to incorporate what you enjoy in a way that is going to work for you.”
Try to find exercise, eating and lifestyle habits that you actually enjoy and that align with your goals. Starting with small shifts will allow you to make sustainable behavior change over time.
Set non-weight related goals
Shifting your goals from changing the number on the scale to other health markers can help you maintain mental health.
This might mean focusing on increasing your energy levels and mood, improving your relationship with food, gaining the ability to bend and stretch without difficulty, or lowering your blood pressure and sugar.
This is especially important because how much your weight goes up or down is based on your individual physiology, Peterson says. Eating nutritious foods and moving your body can help you feel better, but they do not necessarily guarantee your size will change.
“You have control of your behavior but not how your body responds to it,” she says.
Celebrating non-weight wins along the way can be encouraging and help you adopt new habits without feeling discouraged by the scale.
Eat without distractions
The more you can slow down and focus on eating, the better you’ll be able to notice hunger cues and hear when your body is hungry and full.
This means putting away your phone, closing the laptop and allowing yourself to savor your meal. Not sure how to slow down? Notice the looks, smell and flavor of the dish, and try to spend time chewing each bite.
Pay attention to signs it’s time to back off
Gaining and losing weight is complicated, and it’s easy to get caught up in numbers and lose sight of what feels good in your body.
Try to notice warning signs that things might be going too far, like difficulty sleeping, difficulty recovering from workouts, loss of menstruation, weight cycling and a preoccupation with food, Peterson says.
If you notice these things popping up, it’s a sign to talk with your doctor and reevaluate if your current weight management plan is working for you.
Remember: Your weight does not determine your worth. The idea of managing your weight is to be able to feel the best you can within a lifestyle that is meaningful for you.
“I want to expand the lens of what it means to help people feel good in their bodies,” Riddle says. “Well-being goes beyond weight.”