"This is a troubling statistic: with all our efforts to improve efficiency, increase yields and raise production in the field we sacrifice half of it in avoidable losses in the early part of the food chain, and wastage in the latter," the report notes.

Besides food waste, the report's authors highlights the inefficient handling of the world's finite fresh water supplies as another key factor that has been and will continue to lead to an increase in the number of people who are starving or undernourished around the world.

"More than one-fourth of all the water we use worldwide is taken to grow over one billion tons of food that nobody eats. That water, together with the billions of dollars spent to grow, ship, package and purchase the food, is sent down the drain," Stockholm International Water Institute executive director Torgny Holmgren said in a statement.

"Reducing the waste of food is the smartest and most direct route to relieve pressure on water and land resources. It's an opportunity we cannot afford to overlook," he said.

Trading meat for veggies
The alternative, according to the authors of the report, could see the world's population forced to give up eating meat in favour of a virtually vegetarian diet.

As it stands, humans now derive about 20% of their protein from animal-based products. However, without changes to the food supply system, as the world population grows by another 2 billion in the next 40 years, that ratio may need to drop substantially.

"There will not be enough water available on current croplands to produce food for the expected population in 2050 if we follow current trends and changes towards diets common in Western nations," the report warns.

"There will, however, be just enough water if the proportion of animal-based foods is limited to 5% of total calories, and considerable regional water deficits can be met by a well organised and reliable system of food trade."

Highlights from the report's recommendations to policy-makers include:

• a move away from unsustainable agricultural reliance on groundwater in favour of better “green water” management including more efficient irrigation and development of local rains
• beyond improved food production, more attention to the role of unclean water, inadequate sanitation and poor hygiene as contributors to malnutrition
• closer scrutiny of the water resources lost from one region to another when foods are exported
• adoption of an "Integrated Water Resources Management" approach to private-public partnerships that account for the role water plays in the security of food supplies, as well as energy production, health and international relations

This year's World Water Conference in Stockholm is being attended by more than 2,500 politicians, researchers and experts from the UN and other non-governmental agencies. Organized around the theme “Water and Food Security," the conference features more than 100 sessions examining the challenges and solutions for managing the vital resource.

While its warning message is dire, the report released to kick off the week-long gathering nevertheless strikes an optimistic note.

"The bad news is that we are wasteful; the good news is that means if we reduce waste we can feed everybody without additional resource use."