As it is a problem of universal occurance today, I would like to make a few general suggestions that may be of some use across the board. I think it is important for us to understand the two main causes of the problem, which seem to be logically linked.
I envisage public ignorance and indifference to what constitutes a given individual's nutritional needs as a significant cause of obesity and some deficiency diseases distributed throughout the world. Sometimes, aggresive and colourful advertising appears to affect the eating and drinking habits of even those who know what food and drinks may best serve those needs.
Therefore, it would be useful to make nutrition an integral part of education of everybody from the earliest possible age. Moreover, it should reinforce the individual's ability to resist harmful advertising, and it should help each person to understand that the traditional food and drink of a given area would best serve the nutritional needs of the people there. Of course, these may be improved, and new food items may be introduced, but its replacement for commercial or fashion reasons could be disastrous.
It is crucial for people to understand that one's nutritional needs are also influenced by the climatic conditions. For instance, in tropical countries, one requires less carbohydrates to sustain body heat for simple physical reasons, while in cooler climes, maintainance of body temperature requires a relatively greater intake of the same item.
At the same time, one must understand that when the use of 'labour saving' devices becomes prevalent, individual energy needs diminish in proportion. Then, if one does not adjust one's diet appropriately, obesity becomes inevitable unless one finds some other suitable outlet for the excess energy. I do not regard eating and drinking as simple fuel intake, but we should understand and pay attention to their fundamental purpose. I think this should be a part of one's general education.
Now, a word about the second major cause of malnutrition. I think agricultural production of an area should be subserviant to the nutritional needs of the inhabitants there. While the chemical ingredients of those needs such as proteins, carbohydrates, etc., are universal, their specific sources and required quantities are subject to an immense variation. Climatic and geographical conditions play a significant role in determining to what sources one may resort to obtain them, eg. variation in cereal types and sources of protein. Traditional eating habits have been fashioned by our awareness of this for a very long time, hence, should not be dismissed as some tend to do.
But unfortunately, in many countries, agricultural production is governed by economic considerations which are motivated by the desire to gain profit. I think most people have heard about instances where farmers were induced to switch over to growing 'cash crops' instead of food crops, which in turn increased the incidence of under nourishment in the area. A different variation of the same sad theme is getting the farmers to export a food crop for more cash leading to a shortage of a local food item. This happened in Senegal and the Cameroons when most of the annual peanut production was exported for cash, and as a result the local chidren began to suffer from protein deficiency as peanuts were an important source of their protein intake.
I think the local agricultural producers and consumers ought to get together to ensure that they first act for their mutual benefit, and then, if it does not entail any environmental degradation, producers may help out their neighbouring communities to make up their short falls. Under careful supervision, such help may be extended to national, regional, and even global levels. But in each case, the guiding principles are the nutritinal needs of the individual at a given place, and never the 'needs' of the abstract entity, the economy.