Do you agree with this Bill?
It's virtually impossible - no matter what you eat - to gain fat after a workout - provided it was a real workout and not something silly involving water aerobics. The time frame that goes for about one hour after lifting weights.
Although gaining fat during this time period is unlikely, it's very likely that you will build muscle provided you feed your body the protein it requires.
It is due to insulin (insulin carries glucose and amino acids to muscle cells). Insulin is like a bus driver, taking the food to the fat cells for storage or to the muscles for building. The route is determined by exercise - if you've just finished lifting weights, insulin will take the nutrients directly to muscle for repair.
Now that doesn't mean a bag of popcorn and a coke. It means a pre-workout drink with some carbs to fuel the energy needed. Just don't go overboard with it. A very simple thing to do is get a 32 OZ Nalgene and fill it 3/4 with water and the other 1/4 with Gatorade. Bare minimum. There are certainly better options ranging from low cost to high cost amino drinks, but working on heavy lifts while hungry will yield little.
Afterwards I simply mix up a protein shake with about 50 grams of Protein using Almond milk. You can use the same Nalgene (after rinsing of course).
Experiment and see what works for you. If you have something you are already doing, feel free to share at Warrior Talk's Fitness Section.