# Perspective: Fat Reduction Campaigns and Their Impact on Young Children—The Root Cause of the Obesity Epidemic?

## TL;DR

This paper suggests that fat reduction campaigns in early childhood may have contributed to the obesity epidemic by altering metabolism and energy regulation.

## Contribution

The novel hypothesis that early fat restriction could be a root cause of the obesity epidemic is proposed.

## Key findings

- Children's fat intake has decreased significantly, often below recommended levels.
- Early fat restriction may lead to a 'thrifty metabolism' and leptin resistance, promoting obesity later in life.
- Structural and metabolic similarities between undernourished and obese individuals suggest early energy restriction programs obesity.

## Abstract

After decades of rising obesity rates, key questions about the causes of this epidemic remain unanswered. One major puzzle is the discrepancy between increasing obesity prevalence and decreasing energy and fat intake. Campaigns to restrict fat intake to prevent obesity have led to a decrease in fat consumption; however, little attention has been paid to the specific effect of this advice in early life. This review aims to evaluate the impact of such campaigns on the dietary habits and future health of young children, and to investigate the potential contribution of early nutritional changes to the obesity epidemic. Available data reveal that children’s fat intake has fallen drastically in recent decades, often reaching levels well below official recommendations. Reducing fat intake is not appropriate in early life, when fat is essential for brain development and meeting high energy needs. Early energy restriction can alter the hypothalamic axis, leading to a reduction in leptin level and irreversibly imprinting a “thrifty metabolism.” These mechanisms may decrease basal energy expenditure, develop leptin resistance, and promote fat storage. The unexpectedly high number of structural, functional, and metabolic similarities between undernourished individuals and subjects with obesity suggests a role of early energy restriction in programming obesity. A person with obesity can then be considered an undernourished individual covered with high-fat stores that cannot easily be used. By affecting the early period of life, advice to reduce fat intake to combat obesity may instead have contributed to its increase. This shift in thinking, from overnutrition to undernutrition, to explain the origin of obesity, highlights that fat intake should not be restricted in young children. The novel hypothesis that fat reduction campaigns, by affecting early life, could be a cause of the obesity epidemic should open new avenues for research and prevention.