Are these estimates accurate?
We should start by clearly stating: These are estimates. They are estimates based on economic models which are based on implicit and explicit assumptions to make them simpler. The only way to truly know if they are accurate is to empirically test them by spending US$40b every year as recommended, and seeing if it cures world hunger.
Failing that, we can look to see how different economists model the problem to see if the numbers are at least consistent with other estimates.
The Global Cost of Reaching a World Without Hunger: Investment Costs and Policy Action Opportunities is a paper that (a) makes an estimate of an approach they recommend, and (b) includes a review of the previous estimates.
Ending hunger by 2030 is estimated to require US$39–50 billion annually until 2030.
So that is consistent with US$40b estimate, only with larger error bars.
Their Table 1 includes a summary of five different papers (from 2015-2017) - that make differing annual estimates to achieve different goals:
- $US265b, to eliminate hunger and extreme poverty by 2030
- $US52b, to reduce hunger to 5% by 2030
- $US30b, to reduce hunger to 3% and improve nutrition by 2030
- $US11b, to reduce hunger to 5% by 2030
- $US7b, to reduce hunger to meet targets on anaemia, child stunting and wasting by 2025
It seems that the estimate given by David Beasley is in the same ballpark as a range of other estimates.
Meanwhile, Cost and Affordability of Preparing Basic Meal Around The World looks at the per meal price for a "Basic Plate" (as defined by the World Food Programme):
Such a meal would contain about one-third of an adult's daily
energy requirement, and is not itself a healthy diet.
They conclude (in Table 2) that the global average cost per day (in 2017 USD) for one meal, using the most affordable items is $0.71, but climbs to up to $1.30 if you include meat.
So the US$0.43 per plate seems low compared to this estimate, but it is hard to say which is more accurate.