What happens if you eat over your caloric surplus

you would gain weight

if you eat more than the recommended amount of calories, and don't exercise it off, then you will start to get more overweight

However, eating too many calories and not burning enough of them through exercise can cause you to gain weight. Most foods and drinks contain calories. Some foods, like lettuce, are low in calories (a cup of cut lettuce contains less than 10 calories).

a mother eats twice as much to support her growing fetus

limiting sugar intake in a mother with gestational diabetes, switching from diving to swimming.   depending on whether the patient is normal weight, over weight or gain will differ depending on that.