Healthy Weight
Obesity is defined as a body mass index (BMI) of ≥30 kg/m2. Being underweight is a BMI of under 18.5 kg/m2
Over 70 million adults in the U.S. are obese. 99 million are overweight.
39.6% of the U.S. population is obese. This prevalence varies by region.
Moderate to high
Fundamentals of Weight and Health
How much weight is too much or too little from a health perspective?
BMI is a standardized calculation that uses weight and height to aid in determining a healthy weight. A normal BMI is considered to be 18.5-24.9 kg/m2. A BMI of >24.9 is overweight, and a BMI of 30 or greater is obese. A BMI >40 is severely obese. In contrast, a BMI below 18.5 kg/m2 is underweight.
Other tools that can be used to determine healthy weight include waist circumference, waist-to-hip ratio, body fat percentage via skinfold thickness and bioelectric impedance. You can find a list of normal values for waist circumference and waist-to-hip ratio here.
Can you be overweight and still be healthy?
Overall, it’s important to note that BMI isn’t everything! For example, one recent study showed that fit people with an obese BMI had similar metabolic and cardiovascular risk profiles to normal-weight individuals. Longer-term studies are needed for a more complete comparative analysis, but the point is that BMI as a measurement doesn’t tell us anything about factors like body composition or weight distribution, both of which affect how healthy someone actually is.
For instance, while excess fat anywhere can have negative impacts on hormone function, extra weight around the abdomen confers more metabolic risk to someone than extra weight carried in the thighs.
How can you tell if your weight is affecting your health?
There are certain measurements that doctors can use to help determine if your health is being affected by your weight. Blood tests include cholesterol panels, blood sugar levels (glucose and hemoglobin A1c), and sometimes the inflammatory marker C-reactive protein. We also assess metabolic health by measuring blood pressure.
Even without any of this, if you find your weight is holding you back from accomplishing things you'd like to be able to do–or if you feel inhibited by heaviness that is causing joint pains or other discomfort–then your weight is affecting your health.
The term “skinny-fat” gets used a lot. What is that?
This non-medical term is usually used to describe people who have an overall thin body appearance, but who have a higher body fat percentage than is healthy for their size.
These individuals typically have a normal BMI, but this fact can be misleading because they may still be at higher risk for weight-associated complications, especially if they carry excess weight in their midsection. One recent study found that this population had an increased overall mortality rate.
Are there any long-term consequences from being over- or underweight?
Yes. Greater BMI is associated with an increased rate of death from ailments such as cardiovascular disease, stroke, diabetes, kidney disease, and various cancers (colorectal, breast, uterine, esophageal, kidney, and pancreatic). The risk is higher if you also have markers such as high LDL cholesterol, low HDL cholesterol, signs of insulin resistance, and high blood pressure.
It’s important to know that the same BMI can mean very different things in different populations. For example, overweight people of Asian heritage tend to have a higher mortality risk at a BMI of 25 than do other groups. This has prompted some to recommend that a BMI of 23 be used as a cutoff to better ascertain risk in that population.
Being underweight also poses certain health risks. It can lead to a weaker immune system, decreased bone density, vitamin deficiencies, difficulty conceiving, and anemia. A study done in 2017 demonstrated that being underweight was associated with an overall increased mortality risk.
What are some reasons for weight gain and weight loss?
Changes in eating habits, physical activity level, or certain medications, as well as inadequate sleep, stress, and various health conditions can result in weight gain or loss.
Some conditions that may contribute to weight gain include underactive thyroid, polycystic ovarian syndrome (PCOS), sleep apnea, and depression.
Conditions that can contribute to weight loss include overactive thyroid, digestive issues, chronic obstructive pulmonary disease (COPD), and depression. Often, weight changes can be related to multiple factors.
Strategies for Losing Weight
What’s the best diet for weight loss?
While no single strategy works for everyone, diet tends to play a significant role in weight loss, and a regular exercise routine is important for keeping that weight off. That said, most doctors typically advise against any type of extreme diet or exercise regimen because these are generally not sustainable long-term.
One important thing to note when thinking about eating and weight is that most people underestimate how many calories they’re actually consuming. To help with this, food scales can be useful to determine appropriate portions. Also, if you’re tracking what you eat, be sure to count everything, including small snacks grabbed on the go.
Most physicians prefer the term “lifestyle change” over diet because it feels less restrictive and more sustainable. As for what approach to choose, the best one for you is typically the one that you enjoy and think you’ll be able to stick with. Paleo, Mediterranean, plant-based (when done healthfully), and low carbohydrate/high protein diets have all been clinically proven to help with weight loss.
Meal timing has also been shown to have a profound impact on weight maintenance for some people, and it has garnered increased attention in the past decade. Intermittent fasting, which restricts eating hours to an 8-12 hour window during the daytime, has other physiologic benefits that have made it a strategy worth adopting if sustainable.
What is the best way to incorporate exercise?
Current Physical Activity Guidelines recommend 150 minutes (or about 30 minutes, five times a week) of moderate-to-vigorous physical activity per week. Specifically for weight loss purposes, many experts recommend longer durations of exercise–up to 60 minutes per day. However, some studies show that even a shorter duration of physical activity has benefits.
For some people, it can be intimidating to start an exercise routine, and it can be helpful to start slowly with measurable, achievable goals that will allow more concrete short-term gains. Successfully meeting these goals will reinforce them and therefore make you more able to continue with and build upon them over the long-term.
For example, you can start off by setting a goal of exercising one day per week. Once that becomes a habit, increase to two days a week, and then increase incrementally from there. It’s relatable to have high aspirations for lifestyle changes, but aggressive goals can be risky because many people end up discouraged by their inability to stick to them. In other words, while a slow and steady style of exercise is not always the best, a slow and steady pattern of exercise is what can result in habit change.
As for what type of exercise is ideal, it really varies by person. In general, it’s best to find something that you’ll enjoy doing. For example, running (arguably the most low-tech way to exercise) doesn’t appeal to everyone, and if it’s not your thing, there’s no reason to force yourself. Likewise, some people prefer to exercise in isolation, while others thrive on the social component. If you aren’t sure what you like, try a few things until you find something that you feel like you can come back to day after day.
The primary goals of exercise are increasing heart rate (thus challenging your cardiovascular fitness), building strength, and increasing mobility and balance. Different types of movement favor improvements in each of these domains. Some activities, like dancing, can help with all of these areas.
The bottom line is to keep experimenting–there’s something out there for everyone! And keep in mind that exercise isn’t just great for weight management. It has a host of other benefits, including improved sleep quality, better mood, and decreased risk of diabetes and heart disease.
How effective is weight loss medication?
When combined with lifestyle changes, people who take prescription weight loss medications lose between 3-10% more of their starting body weight than people who don’t. For those who achieve closer to 10% loss, this can have a significant impact on their overall health.
While some of the medications are better tolerated than others, they can all potentially have side effects. Another thing to consider is the possibility of weight gain after medication discontinuation.
Does bariatric surgery work? Who is a good candidate for surgery?
While the exact amount of weight lost is dependent on a variety of factors and the type of procedure that’s performed, for most people, bariatric surgery helps them achieve a weight loss of >50% of excess body weight that they are typically able to keep off for the long-term.
Bariatric surgery is also helpful in treating associated conditions that sometimes accompany obesity such as high cholesterol, high blood pressure, insulin resistance, and sleep apnea. This procedure involves a lifetime commitment to sticking to dietary recommendations.
Candidates for bariatric surgery are those with a BMI ≥ 40, or those with a BMI ≥ 35 who have other risk factors.
Time and money can be limiting factors for getting help from a nutritionist. What other options are available for nutrition guidance?
In the past few years, a wide variety of apps and programs have helped bridge the gap between coaching support and doing things completely on your own. For example, you can now find several food and exercise tracking apps available such as Noom, My Fitness Pal, Lose it!, Weight Watchers, and others. Particularly effective are programs that incorporate cognitive behavioral therapy (which addresses why we are eating this way and how to make sustainable changes in patterns), health coaches, and group support to increase accountability.
One other important thing to know is that almost everyone has a complex relationship with food. Emotional eating and/or food avoidance is something most people do from time to time.
When food becomes a compulsion, the key to weight management is less about diet and more about restoring a healthy relationship with what you’re eating. Two of the most helpful ways to work on that relationship are mindful eating and intuitive eating. In addition to books and online resources, there’s a whole subset of nutritional counseling that focuses on this type of approach.
Strategies for Gaining Weight
What’s the healthiest way to gain weight?
There are several strategies that can be used to gain weight healthfully. These include eating small frequent meals, and choosing nutrient-rich and high-calorie foods (nuts, nut butters, avocados, olive oil, dried fruits, and whole grains are just a few examples).
The last recommendation, although it may sound counterintuitive, is exercise. Strength training exercise can help you gain weight by increasing muscle mass. It also stimulates your appetite and can support healthy bones to counteract the decreased bone density that’s often associated with being underweight.
Useful Links
Online weight loss resources and reference guides
Connect with our physicians
Jenna Katzman, NP and Nora Lansen, MD are both members of the Galileo Clinical Team. Connect with one of our physicians about Healthy Weight or any of the many other conditions we treat.