It's everywhere – from diet pills to the GLP-1 craze, promotions for healthier foods and commercials for gym memberships at the start of every new year.

Americans want to lose weight, but why is obesity so common that it drives what's among the most popular New Year's resolutions out there? Better yet, what's keeping some other high-income nations, like Japan, from having the same widespread issue?

According to Dr. Michael Hunter, a radiation oncologist from the Seattle area, Japan and Korea lead high-income nations with the lowest obesity ratings while the United States tips the scales at the highest. Japan's use of the "Metabo Law" has been in the news recently as the United Kingdom considers a similar measure to combat obesity; Japan's 2008 law requires waistline measurements of citizens between 40 and 74 in their annual checkups, and those who exceed the limit are steered toward healthier practices.

The Centers for Disease Control and Prevention (CDC) classifies anyone with a BMI of 30-39 as obese, with those of a BMI of 40 or above falling under the "severe" obesity label.

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Data from The Global Obesity Observatory supports the claim, finding that 43% of Americans are considered obese, a percentage exponentially higher than the modest 4.5% for their Japanese counterparts.

Some say it boils down to a combination of activity level, lifestyle, diet and culture, including Hunter, who pointed out the ways Japanese kids head off to school on foot and the population as a whole tends to opt for smaller portion sizes.

To get an inside perspective, Fox News Digital reached out to Japanese YouTuber Yoko Ishii to hear her thoughts about the cultural contrast between the two nations.

"I think that Japanese people begin our health journey starting in elementary school, because, unlike America, children walk to school instead of being driven to school. And then, under our compulsory education, we learn about home economics and that's where we learn about nutrition, balance and so on," she said on Tuesday.

"We cook in class as well, just like in science class, you do experiments. We actually do it and get the hang of it. In school, meals from elementary school to junior high school meals are provided, so that means that, each day, we see the full set of lunch. It's like the ideal lunch, right? It's different in America, but here, there's a soup and white rice and then a couple of other dishes and sometimes a dessert and so on with a milk, so we learn about the balance and what we should eat and what not to eat."

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Ishii said, from childhood, Japanese people establish a lifestyle that involves a lot of physical activity, even walking to school instead of driving when they reach high school. If school is too far away, however, students will often take a train or ride a bicycle, she explained.

But beyond getting to school, students get active there as well. There are no janitors, so students clean the building themselves. There are also a number of school clubs that enable Japanese students to get active.

"Some people go to cultural clubs. But I myself, I belonged to a kendo club. I used to do kendo [a Japanese martial art] and others would belong to judo or baseball or soccer or basketball, volleyball, whatever they wanted to. So we learned to exercise in school," Ishii said.

"I guess that while growing up, we established the system in ourselves to exercise, and to depend on ourselves and think by ourselves."

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Health consciousness is even imbued in the country's variety shows.

"We have lots of health-related shows, so there are quizzes about health and food, and we have to know about it. If you don't, that's kind of an embarrassment, so you have to learn all these things so that you can keep up with other people," Ishii said.

It's even a part of Japan's legal and corporate structure to some extent. According to a website for the country's Ministry of Health, Labor and Welfare, the country conducts annual physical exams – including waist measurements – on eligible people aged 40 to 74 to help prevent lifestyle-related illnesses, particularly related to metabolic syndrome (a cluster of weight-related conditions that include high blood pressure, insulin resistance and elevated bad cholesterol, among others).

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"Specialist staff (public health nurses, registered dietitians, etc.) support those who are at high risk of developing lifestyle-related diseases and who can expect many benefits in preventing lifestyle-related diseases through lifestyle changes," the site reads, translated from Japanese.

The "Metabo Law," aimed at curbing rising healthcare costs in the country, according to a Wall Street Journal report from 2008, urges people with larger-than-accepted waistlines to shed the extra pounds or face "compulsory diet advice and follow-up visits" for several months.

Ishii said the idea hasn't been so shocking to Japanese people, however.

"We don't think about it [the law] much at all. We did start to hear about it, but we were always aware that being in a good health state is important, so nothing really changed," she said.

"I guess the government wants to cut the expense for the medical area. In order to do that, you want to keep your citizens healthy, so that's why I guess that they are trying to raise awareness."