When a person's weight is higher than what is considered healthy for their height, their condition is described as overweight or obese. Bodyweight results from several factors, such as poor nutritional choices, overeating, genetics, culture, and metabolism. Obesity is linked to many health complications and diseases, such as diabetes, heart disease, certain types of cancer, and stroke. Additionally, obesity is the leading preventable cause of preventable death. Despite the negative effects these conditions can have on one's health, more people are overweight or obese today than ever before in history. In fact, obesity is considered a modern epidemic in most parts of the world. Worldwide obesity has nearly tripled since 1975, with about 13% of adults being obese and about 39% of adults being overweight.
The most commonly used method of measuring obesity is the Body Mass Index, or BMI, which divides a person's weight (in kilograms) by their height (in meters) squared. Medically speaking, BMI scores break down as follows:
- BMI under 18.5 = underweight
- BMI 18.5 to <25 = healthy
- BMI 25 to <30 = overweight
- BMI 30 to <35 = obese (class 1)
- BMI 35 to <40 = obese (class 2)
- BMI 40 or higher = obese (class 3 - morbid)
BMI is not a perfect measure. In particular, it can sometimes give a "false positive" score to athletic individuals, whose high BMIs are due not to excess body fat, but to excess muscle. For example, extremely fit NFL quarterback Russell Wilson measured 5'11" tall and 215 pounds in 2016, which gave him a BMI of 30.0, or obese. NBA superstar and wellness enthusiast Lebron James had a BMI of 27.5 in 2012, which qualified as overweight—a clear misdiagnosis. As a result of this inaccuracy, many medical experts are switching to waist-to-height ratio, or WHtR, which compares the circumference of a person's waist to their height. If the waist is more than half the height, (or more than 6/10 the height for those over 50), that person is obese. WHtR is considered much more accurate than BMI, but is also much newer. Over time, as it is adopted by more countries, WHtR could easily replace BMI as the de facto measure of a person's weight health.
Obesity by Country
Obesity rates vary significantly by country as a result of different lifestyles and diets. There is no direct correlation between the obesity rate of a country and its economic status; however, wealthier countries tend to have more resources to implement programs, campaigns, and initiatives to raise awareness and education people about what they are consuming. These are among the healthiest countries globally. Some regions of the world, such as the South Pacific, have seen alarming increases in obesity rates within the past five years. Some governments, such as the United States government, have launched campaigns in recent years to promote healthier lifestyles and being active.
The 10 Most Obese Countries in the World
The most obese country by average BMI is the Cook Islands, which has an average BMI of 32.9. Nauru follows with 32.5, then Niue with 32.4. Samoa and Tonga both have average BMIs of 32.2. Finishing the top ten most obese countries are Tuvalu (30.8), Kiribati (30.1), Saint Lucia (30.0), Micornesia (29.7), and Egypt (29.6). What eight of these countries have in common is being located in the South Pacific. When looking at the percentage of obese adults, the list looks a little different. The most obese country by percentage of obese adults is Nauru, with 61% of adults falling in the obese category. Cook Islands fllows with 55.9%, and Palau just under that at 55.3%. Three other countries have adult populations that are over 50% obese: the Marshall Islands (52.9%), Tuvalu (51.6%), and Niue (50%). Finishing the list are Tonga (48.2%), Samoa (47.3%), Kiribati (46.0%), Micronesia (45.8%). The Pacific island nations appear prominently, with Saint Lucia and Egypt serving as the only non-Oceania countries on either list. Type 2-diabetes is a large concern among the people of many of these countries. Multiple theories exist as to why this particular region is so susceptible to obesity, including the growth of unhealthy fast food, the rise of frying as a means of food preparation, and a possible genetic predisposition toward higher BMIs.
The United States has the 12th highest obesity rate in the world at 36.2%. Obesity rates vary significantly between states](/state-rankings/obesity-rate-by-state), ranging from 23% to 38.10%. This is due to the same dietary, environmental, and cultural factors that cause variations between countries. Diet is primarily to blame, with Americans receiving mixed messages about what they should be eating and how much of it. Faced with mouth-watering advertisements served alongside campaigns promoting daily physical activity and proper nutrition, many Americans opt for fast, cheap, and filling options such as processed packaged food, fast food, and larger portions. This often leads to a diet rich in fat, calories, and sodium (the "butter, sugar, salt" trifecta) and low in vitamins and nutrients.
Top 10 Least Obese Countries in the World
When looking at average BMI, three countries tie for the least obese country in the world, with an average BMI of 21.1: Madagascar, Eritrea, and Ethiopia. Five other countries have average BMIs under 22: Timor-Leste (21.3), Burundi (21.6), Japan (21.8), China (21.9) and India (21.9). Bangladesh (22.0) and Burkina Faso (22.1) finish the list. Japan's presence here is perhaps unsurprising given that the national diet—which emphasizes seafood, freshness, modest portions, and minimal added sugar or dairy fat—is a very healthy approach (as evidenced by the fact that Japanese life expectancy is among the highest on Earth). However, many of the other countries on this list struggle with famine and poverty—which is the wrong way to achieve a low BMI. For a full list of the world's countries and their obesity rates and average BMIs, see the table below.