Highlights: 

The dismantling of the US Agency for International Development (USAID) and reductions in aid budgets by other Western donor countries, including the United Kingdom (40%), France (37%), the Netherlands (30%) and Belgium (25%), over the next 3–5 years threaten to reverse decades of progress in reducing malnutrition. This study quantifies the impact of aid budget cuts on nutrition. The US budget cuts alone will deny treatment to an estimated 1 million children with Severe Acute Malnutrition (SAM), resulting in 163,500 additional child deaths per year. When combined with other donors' reductions, this number could more than double to 2.3 million untreated SAM children, causing 369,000 additional child deaths per year. To address this crisis, it is essential to restore life-saving nutrition interventions, enable governments to scale up essential nutrition programs, increase domestic nutrition funding, and rebuild nutrition data and monitoring systems. Inaction will not only increase child mortality but also inflict long-term economic damages, with malnutrition costing 3-16% of national GDP. Immediate action is necessary to prevent thousands of avoidable deaths and safeguard nutrition for vulnerable populations.