The United States has seen its obesity rates increase dramatically over the past few decades, but as the nation begins to take control over the epidemic, our neighbor, Mexico is seeing rates rise at an alarming pace.

Almost 70 percent of Mexican adults are overweight. Childhood obesity has tripled in the past 10 years and one-third of teenagers are also just as obese, CBS reported. Experts believe that four out of every five obese kids will remain heavy their whole lives. The reason for this rise in obesity, which now comprises 32.8 percent of the adults — compared to the U.S.'s 31.8 percent — is the ever-growing gap in class lines. With over 50 percent of the population living below the poverty line, healthier diets are becoming less affordable for many, who therefore resort to consuming fried snacks, sodas, and fast food, leading to malnourishment and obesity.

"The same people who are malnourished are the ones who are becoming obese," Dr. Abelardo Avila, a physician with Mexico's National Nutrition Institute, told CBS. "In the poor classes we have obese parents and malnourished children. The worst thing is the children are becoming programmed for obesity. It's a very serious epidemic."

Weight-related diabetes accounts for almost 70,000 deaths each year in Mexico and more than 400,000 new cases are diagnosed each year.

The epidemic is growing, in part, because Mexicans have been moving from rural to urban areas where more sedentary lifestyles, less physically-intensive jobs, and growing prices combine to make eating healthy difficult for the poor and working class.

"The result is that for many Mexicans, particularly in urban areas or in northern states, switching to healthier diets is becoming increasingly difficult," UN expert Olivier de Shutter writes in a report on Mexican agriculture and nutrition.

Ever since the popularity of U.S. fast food restaurants grew, more urban Mexicans have been eating pizza, hamburgers, and fried chicken. Grocery stores are also stocked with sodas and cheap, unhealthy snacks. Healthier, more traditional foods, such as broth-based soups, fish, and salads have become more expensive.

"I am trying to keep my children away from it," Noemi Munoz told CBS. "But fruit is so expensive these days and forget about vegetables. We don't have money for much of that."

A national agreement from three years ago between Mexican officials and unions and food producers was supposed to lower the consumption of junk food, but lobbying from agribusiness weakened it, De Shutter said.

"Some important tools to influence consumer behavior, including the raising of taxes on soda drinks and on foods rich in trans-fats or in sugars, were not made part of the National Agreement," De Shutter said. Instead, the agreement blames obesity on consumers' behavior rather than on the food system as a whole, he said.

This link between poverty and obesity is also present in the U.S., where out of 3,139 counties, those that had poverty rates of more than 35 percent were 145 percent more obese than wealthier counties.

Another study also found that the wealthier communities have better access to supermarkets — and fresh produce — than poorer ones. Researchers conducted audits on community fast food restaurants and supermarkets to see how available healthy food choices were.

"The food available in mixed or white high-poverty areas and in primarily African American areas is less likely to enable individuals to make healthy choices than food available in primarily white, higher-income communities," they wrote.

Medical costs for obesity in 2008 were estimated at $147 billion, costing obese individuals $1,429 more than individuals of normal weight. Obesity can lead to a number of conditions, including diabetes, heart disease, and stroke, which are all some of the leading causes of preventable death, according to the Centers for Disease Control and Prevention (CDC).

Source: Baker E, Schootman M, Barnidge E, et al. The Role of Race and Poverty in Access to Foods That Enable Individuals to Adhere to Dietary Guidelines. Preventing Chronic Disease. 2006.