Weight: It is one of the most intuitive indicators to measure the weight loss effect. If you lose weight, it usually means that you have achieved some results in losing weight.
Food intake: it is an important factor affecting weight. Knowing the subjects' food intake is helpful to analyze whether the weight loss effect is related to eating habits.
Waist circumference and hip circumference: Changes in the size of these body parts can reflect changes in body fat content. Usually, the reduction of waist circumference means the reduction of abdominal fat, which is of great significance for evaluating the weight loss effect.
Body fat content: it is a key index to measure the effect of weight loss, because the main goal of weight loss is to reduce body fat, not to reduce water or muscle.
Now, considering the question "Which index can be tested in the human experiment of health food's weight loss function", we need to choose the one that has the least influence on the evaluation of weight loss function. Although the measurement of food intake may be helpful to understand the subjects' eating habits, weight, waist circumference and hip circumference and body fat content are more direct and key indicators.
Based on the above analysis, the most suitable choice is B food intake. When evaluating the weight-loss function of health food, it is not necessary to measure the food intake, because the evaluation of weight-loss effect can be completed by other more direct and objective indicators. This is not to say that food intake is not important, but in a specific human experimental design, if the weight loss effect has been evaluated by other means, then food intake may not need special testing.