Answer to Question 1
An underweight person, especially an older adult, may be unable to preserve lean tissue during the fight against a wasting disease such as cancer or a digestive disorder, especially when the disease is accompanied by malnutrition. Without adequate nutrient and energy reserves, an underweight person will have a particularly tough battle against such medical stresses and face increased risks of mortality following surgeries. Underweight women develop menstrual irregularities and become infertile. Those who do conceive may give birth to unhealthy infants. An underweight woman can improve her chances of having a healthy infant by gaining weight prior to conception, during pregnancy, or both. Underweight and significant weight loss are also associated with osteoporosis and bone fractures. For all these reasons, underweight people may benefit from enough of a weight gain to provide an energy reserve and protective amounts of all the nutrients.
Answer to Question 2
Central obesity may raise the risk of heart attack and stroke as much as the three leading risk factors (high LDL cholesterol, hypertension, and smoking) do. In addition to body fat, weight gain also increases the risk of cardiovascular disease. Weight loss, on the other hand, can effectively reverse atherosclerosis and lower both blood cholesterol and blood pressure in overweight and obese people. Of course, lean and normal-weight people may also have high blood cholesterol and blood pressure, and these factors are just as dangerous in lean people as in obese people. Obese people who do not have high blood cholesterol, high blood pressure, or other indicators of heart disease tend to have more a favorable fat distribution and may be described as metabolically healthy with lower risks for heart disease.
Consequences of normal and inadequate iodine in the diet.
Relative Energy Consumption per Person for Selected Countries
Frequency coding in the nervous system: Threshold stimulus.
Metabolic consequences of adenosine deaminase (ADA) deficiency
Dose-response curve with threshold
The consequences of crossover in the inversion loop in pericentric inversion heterozygotes