Donors have pledged an extra $640m (£490m) to reduce the serious burden of malnutrition, which affects one in three people in the world.

The crisis “endangers the physical and mental wellbeing of present and future generations”, warned Kofi Annan, speaking in advance of the global nutrition summit in Milan on Saturday. “We need further urgent investments so that people, communities and nations can reach their full potential.”

The World Bank has pledged to increase its spending on nutrition to $1.7bn by 2020. The summit will be accompanied by the launch of the 2017 global nutrition report, in which almost every country in the world is identified as facing a serious nutritional challenge.

The annual report found 88% of all the countries surveyed face a serious burden of two or three forms of malnutrition, including childhood stunting, anaemia in women of childbearing age, and/or overweight in women.

Although the number of children under five who are chronically or acutely malnourished has fallen in many countries, the data show the rate of decline is not rapid enough to meet internationally agreed targets. At the other end of the spectrum, the “inexorable rise” in obesity continues, with 2 billion adults obese or overweight and 41 million children overweight.

The likelihood of meeting global targets to halt the rise in obesity and diabetes by 2025 is less than 1%.

At the summit, governments including Ivory Coast, El Salvador and Madagascar committed to extending their nutrition programmes. Philanthropic organisations in India and Nigeria have promised to spend $150m to tackle the problem in the two countries with the highest numbers of malnourished children.

A study published earlier this year showed how the number of people going hungry in the world had increased for the first time since the turn of the century, sparking concern that climate change and conflict could reverse years of progress.

Roughly 815 million people were going to bed hungry last year, compared with 777 million in 2015.

An estimated 38 million people face food insecurity in Nigeria, Somalia, South Sudan and Yemen, while Ethiopia and Kenya are facing severe droughts.

The report found that spending by donors on undernutrition increased by 1% to $5m between 2014 and 2015, but fell as a proportion of official development assistance, from 0.57% in 2014 to 0.5% in 2015.

Melinda Gates, co-chair of the Bill & Melinda Gates Foundation, said: “When nutrition is at the top of the agenda, countries can tap into their full potential … These commitments bring us one step closer to a future in which every child not only survives, but thrives.”