Dairy goats are odd-looking animals. They have huge stomachs to hold the huge amounts of roughage they need to eat. Then, they convert all that roughage to milk and stay skinny. It can be hard for someone who isn't really familiar with them to tell whether or not they are in good shape. You can easily be fooled into thinking a goat is fat when it really isn't.
To tell how fat they are, you check two places.
The first is the loin area, where you press with fingertips to see how much meat is on the bones on either side of the backbone. A skinny goat will have very little, with the backbone sticking up. An obese goat will have so much fat that you can hardly feel the bones and the backbone is in a depression.
The other place is at the breastbone, where she should have some fat covering the bone, but not so much that it forms rolls.
I feed my goats their grain ration on the milking stand, even if I'm not milking them, and take a second every day to check what shape they're in. If they're losing weight, I increase their ration; if they're gaining too much weight, I decrease it, gradually. By checking every goat every day and tailoring their grain ration to their needs, I make sure everyone in the herd is healthy no matter whether they are young or old, pregnant or not. It only takes a second.