Here is the use of the verb "to count" from a text on NHS-diet-veg and fruits
1- Almost all fruit and vegetables count towards your 5 A Day, so it may be easier than you think to get your recommended daily amount.
2- Some portions only count once in a day: 150ml of fruit juice, vegetable juice or smoothie. Limit the amount you drink to a combined total of 150ml a day.
The "count" in the 1st sentence is clear for me, however "count" in the 2nd sentence is confusing and I am not sure about the meaning.
Does "Some portions only count once a day" mean; however many times you eat them, it won't benefit to your body. Even if you eat it 3 times, your body will process it as if you have eaten only once, and get rid of the excess amounts of food?