Understanding the Risks and Causes of Obesity

What Is Obesity?

Obesity is defined by a body mass index (BMI) of greater than 30. BMI is a simple metric that calculates your weight-to-height ratio (kg/m2). Though BMI has its limitations (it doesn’t measure body fat or consider weight distribution), it offers a frame of reference for estimating whether you are underweight, normal weight, overweight, obese, or severely obese, using the following scale.

Underweight:Your BMI is less than 18.5

Normal weight:Your BMI is between 18.5 and 25

Overweight:Your BMI is between 25 and 30

Class 1 Obesity:Your BMI is between 30 and 35

Class 2 Obesity:Your BMI is between 35 and 40

Class 3 “Severe” Obesity:Your BMI is greater than 40

To calculate your BMI, simply enter your height and weight into this freeonline BMI calculator.

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Morbid obesity is defined as being 100 pounds or more above your ideal body weight, having a BMI greater than 35 with at least one serious obesity-related condition, or having a BMI greater than 40. Those with a BMI greater than 40 are also referred to as living with extreme obesity.

Childhood Obesity

Agrowing numberof children worldwide are overweight or obese, which not only increases the risk for being obese as an adult but also increases the risk of developing type 2 diabetes, cancer, and coronary heart disease. (See more on thehealth risksof obesity below.)

Researchers have identified many risk factors evident in thefirst 1,000 daysof a child’s life that are strongly associated with childhood obesity. These risk factors include:

Being born to a mother who is overweight, obese, or living with gestational diabetes

Being exposed to tobacco smoke in utero

High birth weight

Accelerated weight gain as an infant

Poor sleep as an infant

The introduction of solid food before the age of 4 months

Repeated exposure of the infant to antibiotics

Children impacted by these risk factors will not necessarily become obese, and they can influence their body weight and body composition throughout life by eating healthful diets. And a notable aside: Themajority of obesity-related deathsoccur in adults who were a healthy weight in childhood.

Health Risks Associated with Obesity

One of the main concerns about obesity is that it doesn’t always travel alone: People who are obese are at a significantly higher risk formany chronic diseases. Because most data regarding obesity and disease risk comes from observational studies, it’s not possible to definitively conclude if obesity itself increases risk for certain diseases, if obese individuals are more likely to have other risk factors, or if there is some other explanation for the association.

What Causes Obesity?

Obesity is a complex metabolic condition with no single cause. It’s important to understand that multiple environmental, dietary, lifestyle, and genetic factors can influence one’s risk for developing obesity both as a child and as an adult.

Can Diet Alone Cure Obesity?

If you are overweight and have managed to lose weight by dieting only to regain it all back, you are not alone. A2018 meta-analysisof 29 long-term weight-loss studies found that more than half of all weight lost was regained within two years, and more than 80 percent was regained by the five-year mark. It’s common for dieters togain back even more weightthan they lost. More research is needed to understand why it’s so difficult to maintain weight loss.It may be that as we gain extra pounds, the body registers a higher “set point” and will attempt to stay at that weight, through mechanisms such as a slowed metabolism or increased appetite.

While dietary changes may not resolve obesity for everyone, people who eat a plant-based diettend to be leanerthan those who don’t. Rather than calorie-counting and portion control, Forks Over Knives recommends eating a diet of whole plant foods. Whole grains, vegetables, fruits, and legumes contain significant fiber and water, a combination known as bulk.Barbara Rolls, MD, one of the leading obesity experts, says that bulk is key to satiety. These whole plant foods are much lower incalorie densitythan animal products and highly processed foods, and are a phenomenal way to stay full without eating excess calories. Animal-based foods such as meat, cheese, fish, and eggs contain zero fiber, making it easy to exceed your calorie requirements without feeling full. Whole plant foods have also been shown toboost after-meal metabolism.

Because this way of eating doesn’t require calorie counting or portion control, some have found it more sustainable than weight-loss diets. Forks Over Knives has published a number of first-hand accounts from people who, after years of yo-yo dieting, havemaintained weight lossafter going whole-food, plant-based. Read more:

How I Kicked Cheese and Sugar Addiction, Lost 150 Pounds on a Plant-Based Diet

What Giving Up Meat, Dairy, and Processed Foods Did for My BMI, Blood Pressure, and Cholesterol

I Cut My Weight in Half on a Plant-Based Diet

I Went From Obese to the Best Shape of My Life on a Plant-Based Diet

We’ve Lost a Combined 195 Pounds Since Going Plant-Based

After Decades of Failed Diets, I Went Plant-Based and Lost 140 Pounds in 2 Years

From Hot Dog King to Whole-Food, Plant-Based: My 210-Pound Weight-Loss Journey

I Went Plant-Based, Said Goodbye to 100 Pounds, Prediabetes, and My CPAP Machine

Ready to get started? Check out ourPlant-Based Primerto learn more about adopting a whole-food, plant-based diet.