You argue against a method that would (i) determine the average caloric need of adults in a population, (ii) estimate the number of adults whose long-term caloric intake falls below this level and (iii) concludes that this is the number of chronically undernourished adults. And you are right, this is a bad method. But then, I have not advocated this method. More importantly, the fact that this is a bad method does nothing whatsoever to support your method.
Your method, as I understand it, (i) determines the minimum caloric need of adults in a population, (ii) estimates the number of adults whose long-term caloric intake falls below this level and (iii) concludes that this is the number of chronically undernourished adults. By counting only people who do not get even the minimum calories a human being needs under the best of conditions (sedentary lifestyle, slow metabolism, low body weight, no parasites, etc.), your method is secure against over-counting the undernourished. But, and this is my objection, it under-counts. Let me explain why.
Assume your estimate under (ii) is exactly correct: you have estimated that N Indian adults take in fewer than 1800 kcal per day and you are precisely right about this. (Surely this is not an assumption unfavorable to your case.) Looking at these N people, those who really take in fewer than 1800 kcal per day long-term, we must say that each of them is indeed chronically undernourished. So far, so good. But now let's look at the remainder of the population, those who take in 1800 kcal or more per day. Some of them are also chronically undernourished -- because of a heavier workload, because of a faster metabolism, because of higher body weight, because of problems with nutrient absorption, because of lack of specific vitamins, minerals, proteins, and so on. Your method isn't adjusting (increasing) the count of chronically undernourished to account for any of these people.
This is the challenge, Carlo. If you could give a clear response focused on it, then we could all learn something and perhaps overcome this disagreement.
With all best wishes,
Leitner Professor of Philosophy and International Affairs
Yale University, PO Box 208306, New Haven, CT 06520-830