A major IAEA study finds calorie intake, not reduced activity, is the main driver of obesity. Global data confirm the strong link between calorie intake and obesity.
New Delhi (ABC Live): Obesity is one of the fastest-growing public health crises. Nearly 1 billion people worldwide now live with obesity, a condition that has more than doubled among adults and quadrupled among adolescents since 1990. While it was once assumed that declining physical activity explains this rise, new research challenges that idea.
A landmark study published in the Proceedings of the National Academy of Sciences (PNAS), using the IAEA’s Doubly Labelled Water Database, finds that calorie intake and obesity are directly linked — with increased calorie consumption, not reduced activity, as the main driver of obesity in wealthier societies.
Key Findings of the IAEA Study on
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Sample: 4,213 adults (18–60 years) across 34 populations in 19 countries.
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Energy expenditure was higher in industrialized populations, but once adjusted for body size, explained only ~10% of BMI and fat differences.
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Calorie intake, particularly from ultra-processed foods (UPFs), was the dominant cause of obesity.
“Policies focusing on diet quality and reducing ultra-processed foods are more effective than those centred solely on physical activity,” notes Cornelia Loechl of the IAEA.
Global Data on Calorie Intake and Obesity
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Adults with obesity: 650+ million (13% of global adults).
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Adolescents with obesity: 160 million.
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Global prevalence rose from ~1 in 20 (1990) to ~1 in 8 (2022).
| Category | 1990 | 2022 | Change |
|---|---|---|---|
| Adults with obesity | 325 million | 650+ million | 2× |
| Adolescents with obesity | 40 million | 160 million | 4× |
| Global prevalence | ~5% | ~13% | Major rise |
For further reference, see the World Obesity Federation 2023 Atlas, which documents national and regional obesity trends and their link to rising calorie intake.
Country-wise Analysis: Linking Calorie Intake and Obesity
| Country | Adult Obesity % (2022) | UPF Share of Calories | FAO Calorie Supply (kcal/day) | Key Insight |
|---|---|---|---|---|
| United States | 41.6% | ~53% | ~3,770 | Obesity tracks extreme UPF penetration. |
| United Kingdom | 26.9% | 56–57% | ~3,440 | High UPFs, high obesity. |
| Canada | 28.1% | ~48–50% | ~3,590 | UPFs ? half of intake; obesity high. |
| Australia | 32.0% | ~42% | ~3,440 | Calorie-rich environment ? high obesity. |
| Germany | 23.0% | ~46% | ~3,380 | Obesity moderate, UPFs high. |
| Italy | 18.0% | ~10–13% | ~3,380 | Mediterranean diet shields against obesity. |
| France | 10.2% | ~31% | ~3,300 | Moderate UPFs, very low obesity. |
| Japan | 7.6% | 25–35% | ~2,690 | Low calorie supply ? minimal obesity. |
| South Korea | 8.8% | 25–30% | ~2,850 | Obesity still low, UPFs rising. |
| China | 8.9% | Limited data | ~2,940 | Rising calorie supply = rising obesity. |
| India | 5.4% | Limited data | ~2,550–2,700 | Low UPFs ? low obesity, but vulnerable. |
| Brazil | 25.1% | ~20% | ~3,150 | Obesity growing with UPF expansion. |
| Mexico | 32.2% | ~30% | ~3,180 | Sugary drinks drive high obesity. |
| Chile | 34.1% | ~29–49% | ~3,150 | Rapid UPF adoption = rapid obesity. |
Validating the IAEA Report on Calorie Intake and Obesity
Calories Over Activity
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Countries with high obesity (US, UK, Chile, Mexico) also have >3,300 kcal/day supply and 30–57% UPFs.
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Countries with low obesity (Japan, India, France, Italy) show lower calorie supply (2,550–3,300 kcal) and much lower UPFs (10–35%).
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This global pattern confirms the IAEA study: calorie intake and obesity are tightly correlated, while activity differences explain little.
Independent Evidence
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NIH (2020): Diets high in UPFs lead to weight gain even at equal activity levels.
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Lancet Global Health (2019): Per capita calorie supply rose by +500 kcal/day since the 1960s, aligning with obesity trends.
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OECD (2022): UPF-heavy countries consistently show higher obesity rates.
For detailed datasets, see Our World in Data’s Caloric Supply Explorer.
Policy Implications
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Diet is the primary lever — reducing UPFs and calorie-dense foods is more effective than exercise-only campaigns.
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Taxation works — Mexico’s soda tax cut sugary drink sales by 12% in two years.
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Food labelling works — Chile’s labelling law reduced high-calorie beverage sales by 24%.
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Global South advantage — Countries like India can still avoid an obesity epidemic by regulating UPFs before they dominate diets.
Why ABC Live Is Publishing This Report Now
The release of the IAEA-backed PNAS study in 2025 has provided the strongest global evidence yet on calorie intake and obesity in industrialized societies. Governments are currently revising nutrition guidelines, food taxation, and labelling regulations, making this the right time to highlight the data. Publishing this report now ensures that policymakers and citizens understand that the obesity crisis requires diet-focused interventions.
How This Report Is Unique Compared to Other Media Coverage
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Data Validation Across Sources: ABC Live cross-checks the IAEA findings against FAO calorie supply, WHO obesity data, and UPF consumption surveys.
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Country-wise Comparisons: Provides a comparative table of 13+ countries, linking calorie intake and obesity patterns to food environments.
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Policy Integration: Goes beyond statistics to show which interventions (taxes, labelling, subsidies) demonstrably work.
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Global South Lens: Unlike Western media, this report explains why countries like India, Brazil, and China can pre-empt obesity through early regulation.
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Editorial Transparency: By stating why this story matters now, ABC Live emphasizes its role as a data-driven, policy-focused news platform.
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