People are getting fatter especially in low-income countries
Text: Jaakko Kinnunen
The share of overweight people is growing at a considerable pace, says a survey recently published in the prestigious Lancet journal. The study collected data on over 130 million people, the youngest of whom were five years old. This is the world's largest epidemiological study so far. The investigated period covered the years from 1975 to 2016. Professor Terho Lehtimäki from the University of Tampere in Finland participated in the study.
“Diets have changed during the investigated period. Western junk food has spread to low-income countries, which has resulted in weight gain,” Lehtimäki says.
A body-mass index (BMI) of 25-30 means that a person is slightly overweight. If the BMI is over 30, the person is obese, i.e. considerably overweight.
In children and adolescents, the BMI is not the right tool to measure overweight or underweight, because their growth is not completed. That is why the study estimated median weight on the basis of standard deviation (SD) in both the 5-19-year-olds and adults.
Since self-reported figures are often not reliable, only measured length and weight values were used in the study.
Obesity grows fastest
in low-income countries
According to the study, countries can be divided into two groups: In high-income countries, such as Finland and elsewhere in West Europe, weight gain has stabilised. In low-income countries, weight is increasing.
“In West European countries, a partial explanation is that our weight is already high, which makes it difficult to go further up from the current situation. Among the Western countries, obesity in the United States is in a league of its own,” Lehtimäki says.
Particularly high overweight figures can be found in Polynesia and Micronesia. The rise is likely due to changes in diet and lifestyles as well as genetic factors.
“In the small island states of the Pacific, more than 40 percent of the population are severely obese,” Lehtimäki says.
The overweight soon
outnumber the underweight
The study concluded with two main findings concerning the 5-19-year-old children and adolescents. The first finding is that the prevalence of obesity has increased tenfold during the follow-up period. Secondly, the study shows that overweight will replace underweight as a global problem in the next few years.
“If the current trends continue this way, the turning point will be in 2022; there will be the same number of overweight and underweight children and adolescents in the world,” Lehtimäki says.
In 2016, there were about 50 million obese girls and 74 million obese boys in the age group of 5-19-year-olds. On the other hand, 75 million girls and 117 million boys were moderately or severely underweight.
The study concludes that while there are still more underweight than overweight children and adolescents, changes can happen quite quickly, which should be taken into account in policy decisions.
The lowest BMIs are still found in East Africa and South Asia. For example, in India in 2016, underweight and severe underweight occurred in 22.7 percent of girls and 30.7 percent of boys.
According to Lehtimäki, the main reason for the increase of obesity is the change in nutrition. Today, many calorie-rich foods are also available to people in low-income countries.
“Unhealthy habits lead to many health problems and illnesses in later life,” Lehtimäki says.
He points out that fatty tissue as such is not really the problem, but the ensuing diseases are.
“Overweight increases overall mortality at the population level. Many cardiometabolic diseases, such as coronary heart disease, high blood pressure, and high cholesterol, significantly increase with obesity. The same is also true for the metabolic syndrome, which often results in type 2 diabetes,” Lehtimäki explains.
The number of cancers also increases with obesity. Breast cancer is the most common cancer in women. The morbidity of breast cancer rises when people’s weight rises.
Lehtimäki also rejects the idea of the so-called healthy obesity. Sometimes overweight people are described as being overweight but having a healthy metabolism at the same time.
“Healthy obesity is hard to come by in any studies. When overweight people are compared to people with normal weight, the academic community is actively trying to find evidence to corroborate this hypothesis, but so far no hard facts support it,” Lehtimäki says.
There are no shortcuts to avoiding overweight. Lehtimäki mentions the importance of physical activity.
“Physical activity boosts metabolism. If a person left out all physical activity from their lives, it would not take very long to gain five kilograms,” Lehtimäki says.
Abarca-Gómez, L; Abdeen, ZA; Hamid, ZA; Lehtimäki, T; Ronkainen, K; Uusitalo, H (2017): Worldwide trends in body-mass index, underweight, overweight, and obesity from 1975 to 2016: a pooled analysis of 2416 population-based measurement studies in 128·9 million children, adolescents, and adults. The Lancet 390, 2627-2642.