I am an analytical chemist who understands a lot about these estimations in food industry or in environment or in the medicine or anywhere. There is nobody to control all these because most of the national nutrition associations work closely with the food industry.

I furnish you some of the values which give you some important information. Potatoes had in 1978, 87 calories/100g, but it was 68 calories in 1990, carrots 1978, 35 calories and in 1990 only 24. Ragi, in 1978, 240 calories and in 1990 only 194 and avocado, 240 in 1978 and in 1990, 205 calories, if we measure now it may be also different. It can be because of modern analytical methods or the allowed fluctuations in the measurements. Counting calories can make one desperate because what you count is always not correct. Consider the amount and it is easy to calculate and the success is almost pre-planned.