Correct Answer: D

Rationale: Total kilocalories have the greatest effect on body weight as they represent the overall energy intake from all macronutrients combined. While the consumption of specific macronutrients like carbohydrates, proteins, and fats can affect weight management, the total calories consumed play the most significant role in determining body weight. Therefore, choices A, B, and C are incorrect as they focus on individual macronutrients rather than the overall energy balance provided by total kilocalories.

Correct Answer: D

Rationale: Macronutrients are nutrients required by the body in large amounts to provide energy and include carbohydrates, fats, and proteins. While protein is essential for the body, it is not classified as a macronutrient. Proteins are made up of amino acids and serve various functions in the body, such as building and repairing tissues, but they are not a direct energy source like carbohydrates and fats. Therefore, protein is the exception among the listed options, making it the correct answer. Choice A, Fat, Choice B, Polyunsaturated fatty acids, and Choice C, Carbohydrate, are all examples of macronutrients that provide energy and support various bodily functions.

Correct Answer: D

Rationale: The first statement is false because increasing the variety of foods actually helps prevent nutrient excesses and toxicities. The second statement is true because making a dietary change to eliminate or increase the intake of a specific food or nutrient often leads to alterations in the intake of other nutrients. Choice A is incorrect because the first statement is false. Choice B is incorrect because the second statement is true. Choice C is incorrect because the first statement is false, even though the second statement is true.

Correct Answer: D

Rationale: Iron, fiber, and B vitamins are most likely to become insufficient when carbohydrates are eliminated from the diet to lose weight. Carbohydrates are a primary source of B vitamins and fiber in the diet. Iron can also be obtained from plant-based sources like legumes and whole grains, which are often eliminated when carbohydrates are restricted. Choices A, B, and C are incorrect because protein, vitamin K, vitamin A, and vitamin C are not primarily sourced from carbohydrates and are less likely to become insufficient solely due to carbohydrate elimination.

Correct Answer: B

Rationale: The correct answer is B. Magnesium plays an important role in maintaining calcium homeostasis and preventing skeletal abnormalities. It is involved in more than 300 enzymatic reactions, including energy metabolism, insulin activity, and glucose use. Magnesium is vital to the structural integrity of heart muscle and other muscles and nerves. While magnesium does play a role in blood clotting, nerve impulses, muscle contraction, relaxation, ATP energy release, and metabolism of fats, carbohydrates, proteins, the primary physiologic role of magnesium in the body is related to calcium homeostasis and maintaining the structural integrity of the heart muscle. Choice A is incorrect because it includes functions of magnesium, but they are not its primary physiologic role. Choice C is incorrect as magnesium has several known metabolic functions. Choice D is incorrect because although magnesium is involved in ATP energy release and metabolism, its primary role is related to calcium homeostasis and structural integrity of muscle.