John Oliver seems to have gained the reputation of a truth teller. He's a funny man but there are serious problems in his presentations.
He's drawn attention to food waste in the video above, pointing out figures that suggest we waste 40% of our food (!) in the U.S. His segment (like many other such reports) focus attention on produce waste (see the thumbnail image). He correctly identifies the problem with wasting resources and even calls attention to the CA drought.
He isn't telling you the whole story though. All of the problems he cites (resources, methane etc.) have almost nothing to do with produce, let me show you why.
We waste food for various reasons, culling animals from disease, plants from blight, spilling etc. The resource usage is also complicated (growing, processing, transportation, storage etc.). To get a handle on how we waste, we but we need to break production down by food type.
We can look at the loss numbers at the consumer retail level by calorie:
Interesting, seems like we lose a lot in cereals. Is that the problem? Well we need to look at the resource footprints of each type of food to get the real picture. Wheat is the basis of civilization because it is so easy to grow, it takes a lot less energy and water to grow a kilo of wheat compared to a kilo of beef. Beef is, of course, a far denser source of nutrition. What if we factor in, say, the water calorie efficiencies?
Using the numbers from waterfootprint we see the real picture, it is completely fair to say that all the resource wastage is happening in the meat category. There are some caveats to the analysis here:
This is only water that we are using as a proxy for resources, but obviously energy is also very important. I haven't found a good table of footprints that I can use and compare though. I doubt the overall picture is terribly different (transportation costs are likely similar across food groups, I presume meat and dairy have higher storage costs).
I am assuming that food types were aggregated similarly (pretty fair since a large number of groups were used in each study)
These are derived from data published in different years.
The calorie water efficiencies vary in different categories of meat (pork and chicken do much better than beef)
The pictures will change when you look at protein and fat efficiencies, but you need to compare sensibly e.g. asking about the fat production efficiency of a potato is nonsense.
There are likely a few more (e.g. I could have a typo in my R code), but it is extremely hard to imagine what sort of error could lead to a material change in this picture. Saving produce is great and all, but eating some wilted lettuce or an ugly tomato amounts to a drop in the ocean.