I eat the same foods year round, only change the quantities. Stomach issues and allergies are part of it, but mostly because like others here, I eat for a purpose and reason: it's fuel and ammunition for what I want to accomplish with my body. Anything that isn't helping me get to my goal, is hindering my path to the goal.
When I was younger and competing, I used to binge on junk foods in the off-season and then have to work really hard to cut off the excess fat gained before my contests. You can get away with that to a certain extent when you're young, but it's much harder to get and stay lean as you get older.
Now that I'm over 50 and no longer competing, I just try to stay reasonably lean and in shape all year; I'm not so worried about bulking up but just trying to maintain the mass that I've already built over 33 years of training in the gym.
I try to eat high protein, high fat, low carb meals during the day to stay alert and a little hungry, and then try to eat more carbs for dinner to increase satiety and serotonin levels to help me sleep better at night.
Breakfast is always 6 eggs, 2 slices bread, 2 slices of cheese.
Lunch is almost always a chicken breast on 2 slices of bread, with half of a 32-ounce bottle of kefir.
Intra-workout and post-workout, whey protein mixed with Gatorade.
Dinner varies a little bit, but is always a big piece of meat, chicken, or fish with rice and plenty of vegetables: broccoli, cauliflower, brussels sprouts, green beans, asparagus, spinach, carrots, all washed down with the remaining half of the 32-ounce bottle of kefir.
If I go out to dinner, I usually have salmon or swordfish with rice and vegetables, although I do love a good steak and baked potato as well.
Never drink soda or eat snacks, never drink alcohol, rarely I will have a little ice cream if I am out somewhere with the kids and we are all having a good time together.
Eating like this year-round has enabled me to stay lean, with prominent veins and abs, all year long. I will just increase or decrease the amounts of food, but keep the foods the same, if I am trying to add a little more muscle or cut a little bit of fat.
Consistency is much more important in life than intensity ever will be. Stay consistent all year long and then it's much easier to see what works for you and what doesn't, and exactly what you have to cut out if you are getting ready for a photo shoot or contest.