Weight gain is a complex issue. But there is little doubt that the current food environment in Western countries – heavy in highly processed salty, sugary, and fatty food – has a big role to play. Most of the salt eaten in our diet has been added to food in the manufacturing process. This is in contrast to the small amount of salt naturally present in most foods or what is added at the table or at home in cooking. Salt can be a desirable taste, increasing the palatability of foods in addition to helping preserve it; that’s why it is commonly added in processed foods.
Combining salt and fat together is thought to be a potent combination in helping to promote passive over-consumption foods. Just think of how moreish salty chips can be. Having a greater liking for salty and fatty foods is associated with eating more kilojoules overall, uncontrolled eating, and overweight in children. This link between overconsumption of food and its degree of saltiness is considered stronger than having a liking for sweet and fatty foods.
Teasing out further how salt may influence the over-consumption of fatty foods, sensory researchers from Deakin University recruited 48 healthy adults to take part in a tasting panel. Over four lunchtime sessions (following on from a standardised breakfast that morning), each person ate a meal of macaroni and cheese where the fat and salt content had been manipulated. The four meal combinations were low-fat/low-salt, low-fat/high-salt, high-fat/low-salt and high-fat/high-salt. Participants were encouraged to eat as much as they wished until feeling full. Eating rate, meal agreeability, and subjective ratings of hunger and fullness were also taken.
Salt promotes over-eating
Eleven percent more kilojoules were consumed when the meals eaten were high in salt. And this was irrespective of if the fat content was high or low. The fat content of the meal didn’t result in people eating more food by weight, but because of its greater energy density, that meant more kilojoules were eaten.
It is probably true that macaroni and cheese has:

A. Average salt content

B. High salt content

C. Low salt content

D. not enough information
B
The passage states that most of the salt eaten in Western countries today has been added during food manufacturing, rather than added naturally. It also mentions that it is commonly included to increase palatability and preserve foods. Macaroni and cheese would almost certainly have a high level of salt as well as fat, so answer B “high salt content” is correct.
- The other answers are incorrect because they do not match the given information: 
A) Average Salt Content - This option means macaroni and cheese contains an amount of salt similar to what people usually eat; however, this contradicts the information in paragraph 1 about how much additional manufactured salts we consume compared with natural ones (which occur only at very low levels). Therefore A can be eliminated from consideration. 
C.