2.1. Naturalistic designs

There are two forms of naturalistic designs that can be applied to the issue of the "consequences of low-level energy balance" question. One design is based on identifying the distribution of levels of intake in a population. Individual intake is determined, and individuals and households are classified by levels of intake. Communities can be similarly classified by the proportion of low-intake individuals/households.

Data collection and analysis can be based either on the full "intake/expenditure" distribution, or subjects (households) can be selected out of this distribution based on specific characteristics.

A second type of naturalistic study could be termed "natural experiment", for it is based on identifying events or conditions that alter the energy balance, either by increasing or decreasing intake and/or energy demands. In either case, the term "natural experiment" is used to emphasize the fact that the investigator does not manipulate the energy variable, but takes advantage of conditions that potentially alter energy balance. The determination that the energy balance is shifted to a different level is a primary requirement of this design.

Studies that make use of the distribution in the population assume that the patterns that emerge have some time depth, that they reflect "long-term consequences" of low intake. On the other hand, studies that utilize "natural experiments" (e.g., outmigration by male household members, short-term variations in food availability or labor demand) require a longer time frame for data collection, as do studies based on experimental designs.