That absolute statement is absolutely false. Say, I have a chicken that can be feed from left-over bread or wheat. I can store the wheat basically indefinitely, so there is no spoilage. Also, I cannot use wheat directly, so it is unusable calories for me. But I cannot store bread for very long, so there is spoilage. Now, using the chicken, I can convert the spoiled bread into eggs and meat, useful calories for me.
Say 10% of the calories produced for me at a human go to waste. And I can convert them at 25% efficiency to usable calories via a chicken. Then I have just increased the yield of usable calories by 2.5%. In consequence, I need to buy less and thus emissions can be reduced.
Say 10% of the calories produced for me at a human go to waste. And I can convert them at 25% efficiency to usable calories via a chicken. Then I have just increased the yield of usable calories by 2.5%. In consequence, I need to buy less and thus emissions can be reduced.