The flavor that is lost

The flavor that is lost by making the cookies with little or no fat is often replaced by excess sugar or starches, and the end result is that the cookies have close to or as many calories as the originals.

flavor / is replaced = main thought

(that is lost by making the cookies with little or no fat) = adjective clause describing flavor

flavor lost by little or no fat .....how come ? is it true ?

flavor comes by excess sugar or starches ?

A lot of flavour in food comes from the fat in them. There are a number of studies about this.

Consumers want to buy lower-fat food products, but they think the low-fat foods don't taste as good once the fat in them has been reduced.

In order to improve the flavour of the low-fat food products (and keep the low-fat labelling), producers add sugar and/or starches to the products.

When the producers add sugar and/or starches to the food products, they reduce the health value of the food.

glad to know that information . That was very much helpful.

I don't believe that this a common collocation, Tintin.

really really [really] helpful [more casual use]

very, very [very] helpful

exceedingly helpful [more formal use]

The flavor does not come from the fat but that fat prevents the flavors from escaping with the steam vapors. The fat hold the flavors in. Taste fat itself there is no flavor.