Answer
Oils are rich in fat and eating too much makes it easy to gain weight.
Step-by-step explanation
Why is the word "fat" correct to fill in the first blank?
Because oils, including those made from plants, are essentially concentrated sources of fat in our diets, fat is the appropriate word to complete in the first blank.
Triglycerides, a type of lipid or fat molecule, make up the majority of the molecules in oils. When we eat oil, whether by frying, dipping bread in it, or adding it to salad dressings, we absorb a lot of fat calories compared to other nutrients.
Why is the phrase "gain weight" correct to fill in the second blank?
The right answer for the second blank is "gaining weight," as eating too much oil can easily lead to eating too many calories, which are afterwards stored as body fat and cause weight gain.
Oils are so high in calories that it is simple to consume more fat calories from oil than we burn off through exercise in a given day. Even very tiny amounts of oil used in cooking can soon add up to several hundred "empty" calories that give energy but few vitamins and minerals.
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