I recently learned that about 38% of the calories consumed by pregnant women in Mexico comes from the consumption of sugary drinks, like sodas. Mexico also has the highest consumption of Coca-cola per capita of anywhere else in the world. Not surprisingly, Mexico also has the highest growth of obesity rates in the world. Mexico’s geographical proximity to the United States does not appear to help, since the highest prevalence of being overweight and obese is in male adolescents who have migrated to the United States.

Homero Martinez, a paediatrician and a senior researcher at the RAND corporation, who is originally from Mexico, was recently at a breakfast seminar in central London organised by the NGO C3 Collaborating for Health. He was there to present the results of the most recent national health and nutrition survey which took place in 2012 (he stressed he had no involvement with the survey, so the results are not his). This survey encompassed 50 528 households in 32 Mexican states, which amounts to 194 923 individuals (Mexico has a population of around 115 million people).

Considering that Mexico is now a middle income country, the Mexican population is not afflicted by a lack of calories. Only 2.8% of children under 5 years old have a low weight for age, while 9.7% are obese. But the figures get worse in older children, adolescents, and adults. The prevalence of adults who are overweight is 42.6% and 35.5% (males and females), and the prevalence of adults who are obese is 26.8% and 37.5% (males and females). The prevalence of abdominal obesity (having a waistline over 90 cm in males and over 80 cm in females) was 64.5% and 82.8% in males and females, respectively. Martinez pointed out that this is linked to cardiovascular events in adults aged 20 and over.

Even though the calorie intake of the Mexican population is not sufficient in terms of quantity, in terms of quality it is suboptimal due to a lack of micronutrients in the diet. There is a high prevalence of anaemia across all age groups, and that is particularly worrying in toddlers, infants (with prevalence of over 20% in both sexes) and pregnant women (with a prevalence of 17.9%). Martinez stressed that anaemia needs to be addressed early in life, because later on it leads to impaired cognition, and decreased IQ, and work capacity.

Compared with previous surveys (in 1988, 1999, and 2006), there has been an increase in the percentage of the population that is both overweight and obese across all age groups, and thus the normal distribution curve of Body Mass Index in the population has basically shifted to the right. The prevalence of obesity in adults was 24.9% in 1999, 32% in 2006, and 35% in 2012.

What is also extremely concerning is that on average, households reported spending 54% of their monthly income on food, with 70% of households reporting food insecurity, which is more severe in rural areas. This perhaps reflects the fact that about 49% of households are experiencing poverty.

But it is not all bad and there are some positive signs too. Some indicators of infant feeding like minimum food diversity and the consumption of iron rich foods have improved. Moreover, the prevalence of anaemia across all age groups, including in both pregnant and non-pregnant women, is falling.

In his talk, Martinez did not talk about the government’s response to the obesity epidemic. As expected, he was asked about it during the discussion and he said that the government is trying to increase the health insurance coverage of the population. This entails making available low cost packages of medical care, as only about 65% of the population are covered and therefore people often have to make significant out-of-pocket payments to pay for their healthcare. He also said that the government is providing subsidised programmes to improve nutrition at a population level by providing subsidised milk or school lunches. Moreover, a 20% tax on fizzy drinks is expected to be voted on in parliament very soon.

I left with the feeling that it is very hard to change the status quo because of fierce lobbying from soda companies, and even opposition from small street shops, who survive due to the sale of fizzy drinks. After all, which company would want to kill the goose that lays the golden eggs?

But the bottom line is that obesity in Mexico is an extremely serious public health problem with tremendous future implications for the country’s healthcare system, and I fear ongoing efforts are simply not enough.

Tiago Villanueva is the BMJ editorial registrar. He was treated to a free healthy breakfast at the meeting, comprising fruit, yoghurt and granola.