High junk food consumption in childhood increases risk of unhealthy body fat by early adulthood

With economic development, it would seem that undesirable side effects such as the mass production and consumption of highly processed junk foods, obesity, pollution and lifestyle diseases also increase in prevalence. A new paper published recently in the journal JAMA Pediatrics reports consistent and significant associations between the increased consumption of such ‘ultraprocessed foods’ by children in the UK, and a higher risk of obesity, increased body fat percentage, and overall body mass, by the time they reach young adulthood.

The team said:

Through a lack of regulation, and enabling the low cost and ready availability of these foods, we are damaging our children’s long-term health. We urgently need effective policy change to redress the balance.”

What are British children eating?

As defined by NOVA, ultraprocessed foods (UPF) are industrially formulated foods that have been through a combination of sequential processes, whether physical, chemical or biological. These are typically empty of nutritional value, but rich in energy density.

Such foods have high concentrations of sugar, salt, saturated fats, but low levels of proteins, dietary fiber and micronutrients. They are addictively tasty, but cheap, easily available, ready-to-eat, and marketed in a highly attractive format, especially to children.

Common UPFs include potato wafers, industrial breads, fizzy drinks and frozen meals or shelf-stable meals.

In the US and the UK, such dubious practices have led to a mass shift to UPFs on the part of children, representing about two-thirds of their daily calorie intake. This implies that UPFs provide over 40% of the total diet, in grams, and over 60% of total calories.

This change is not limited to these countries, though it may be most prominent there. Instead, this global shift has been simultaneous with a rise in the prevalence of obesity among both children and adults worldwide.

The study shows that the increase in UPF consumption by children is linked to a higher risk of becoming overweight or obese.

How was the study done?

Earlier studies have shown that increased UPF consumption increases body mass in adults, linked to the intake of too many calories. It is also associated with higher prevalence of obesity, type 2 diabetes, cardiovascular disease, cancer and death among adults.

The current study was led by the Imperial College London in the UK. The data came from the Avon Longitudinal Study of Parents and Children (ALSPAC), covering over 9,000 children from 7 to 24 years of age, over 19 years. All the children were assessed for body mass index (BMI), fat mass index (FMI), lean mass index (LMI), and percentage of total body fat at annual or almost annual visits.

In addition, a food diary for three days was kept for two weekdays and one weekend day before each visit. The foods were then classified as unprocessed or minimally processed; processed cooking ingredients for seasoning or cooking the unprocessed foods; processed foods (using the above cooking ingredients, or salt, or sugar); and UPFs.

Based on these, the children were classified into fifths, from the lowest to the highest UPF consumption, ranging from 23% to 68%, respectively. This would indicate that a full fifth of the children in the study got almost 80% of their calories from UPFs.

Children who ate the most UPFs were more likely to have poorer or less educated mothers. The major UPF was fruit drinks, making up a little below a quarter of the total in the fifth quintile. Fizzy drinks made up about 12%, with ready-to-eat foods at 9% and industrial breads at 6%.

The children who ate the least UPFs had mostly unprocessed or fresh foods and drank beverages such as water/ tea, milk/unflavored yogurt. In fact, each of these pairs was used by at least a fifth of the children in this quintile.

High UPF consumption associated with higher fat mass

As early as nine years of age, children in the highest-UPF-consumption profile had higher body fat mass. Their FMI at this age was already 0.27 higher per year relative to those in the first quintile and increased at 0.03 more per year

The mean body fat percentage was also higher. LMI, and its rate of increase, as well as that of the mean body fat percentage, were, however, uniform across quintiles.

Compared to the lowest quintile, children in the three highest quintiles of consumption were heavier, had more fat around their waists, and the average weight in these three groups increased more sharply. Thus, those with the highest consumption showed 0.20 kg per year more of weight gain than those in the lowest, and those in the fourth quintile had 0.10 kg more of weight gain per year.

These children showed higher growth trajectories, of 0.06 more per year for the BMI, 0.2 kg more per year for weight, and 0.17 more per year for waist circumference. The higher the consumption of UPF, the larger was the increase.

By the time they were 24, those who had the highest UPF consumption had a BMI  higher by 1.2 kg/m2,  with a 1.5% increase in body fat percentage, compared to those in the lowest quintile. Similarly, they were approximately 3.7 kg heavier, with a waist circumference 3 cm greater.

What are the implications?

This is the first study to explore the link between UPF consumption and obesity in children over such a long period. Researcher Christopher Millett comments: “We often ask why obesity rates are so high among British children and this study provides a window into this.”

Earlier studies from Portugal, Spain and Brazil, for example, which failed to show such associations could have been because children in those countries have much lower UPF consumption. In contrast, it is widely acknowledged that children who consume more beverages sweetened with sugar are more likely to be obese, agreeing with the results of this study.

If these patterns of UPF consumption continue or intensify among children, they signal: 1) the potential for a higher consumption of these unhealthy foods lifelong due to the establishment of dietary habits; and 2) the danger of a future large-scale increase in obesity, type 2 diabetes, hypertension, cardiovascular disease, and cancer, as well as a higher death rate, among adults.  

Despite the high short-term profits of the UPF industry, governments must act to reduce the consumption of these foods. For instance, such foods could be taxed and fresh or unprocessed foods subsidized to incentivize a shift to the latter.

Voluntary action by UPF producers is unlikely to create adequate impact, especially in instances where these foods are heavily marketed and target children. This should be restricted, and bold labeling in a prominent place made mandatory.

Moreover, some regulations ignore UPFs as long as they meet regulations about reduced sugar, salt and overall calorie content.

This study does not provide insights on what drives the association, which could be a field for further research.

The team writes:

Only mandatory policies that target UPFs holistically, with globally cooperative strengthening of regulations and trade agreements to reduce the supply and consumption of UPFs, will counteract the substantial burden of UPF consumption on the environment and health care systems worldwide.”

Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.