Individual Variation

Glycemic index numbers are not fixed biological constants because they are measured in people who differ biologically. Glycemic index values can illustrate a general principle but should not be treated as precise for every individual. Different tables or sources may list different glycemic index values for the same food. Randomized assignment rather than self-selection in clinical trials may mask advantages that arise from alignment with personal preference. The same food can produce different blood glucose curves in different individuals. Adaptation to fasting varies between individuals, with some habituating over time and others never fully adjusting. Some individuals become irritable during fasting periods and therefore do poorly with intermittent fasting.