What is a “good” diet?
Millennia of biological and cultural evolution created the great diversity of human nutritional styles. Humans have explored an extraordinary variety of animal and plant foods together with innovative preparative methods — particularly cooking — as aids to digestibility and effective release of nutrients from food. Where the luxury of choice in dietary matters was possible we must assume preferences were guided by taste and the capacity of their food to supply enough energy for the daily grind. The value of a diet for long-term health or longevity was not an issue that could be addressed objectively in the past. A change came in the 19th century when curious minds began to see food in terms of chemistry and physics. Its constituents — protein, carbohydrate and fat — were recognised as sources of energy and building blocks needed for growth and maintenance of the body.
But what was the optimal composition of a human diet? This was not easily determined; indeed the working standard adopted by nutritionists is the average composition of the diet of healthy people in the industrial world. They recommended that high quality protein should provide about 15% of energy intake (about 0.8 grams per kilogram of body weight per day), although more recent thinking suggests this should be increased. Fat intake should be no more than 30% of total energy and complex carbohydrates should fill the gap (ie about 55–60% of total energy). Curiously while carbohydrates are the biggest component there is little evidence that they are essential for human well-being.
Providing calorie consumption matches physical activity the precise proportions of these macronutrients are not crucial for health and longevity. Our focus at the IFBB is on a much more important issue: the large range of biochemicals needed in small amounts (micronutrients) by humans. Deficiencies of these can have very significant consequences for many aspects of human physiology, including the ageing process, neurological functions and behaviour.