I have been weightlifting for a while now, and one thing that I used to do (though not anymore) was bulking and cutting. Cutting involves a phase where you look to reduce your body-fat percentage by reducing your caloric intake. After bulking, where you eat a bit more than what your body needs (350-500 extra Calories per day for me), cutting - in my case eating 250-300 Calories less than I needed - seemed like hell. That's not too bad though... Some people reduce their caloric intake by over 900 Calories per day to reduce their body-fat. Now THAT is strict!
Anything that allows me to stay within my boundaries of what I need to take in so that I can grow. I used to be super strict (7-8 meals a day, carefully measuring out each gram, etc.), but over time and loads of research, I started to follow a more structured IIFYM (If it Fits Your Macros) diet.
Having only a certain amount of calories a day, drinking only water (same amount every day), having no junk food, having certain amounts of sugar, having recommended amount of dairy, protein, grains, veggies/ fruit, and eating every meal that the same time every day.
Eating a mostly raw food, plant-based diet. No sugar or processed foods (essentially anything that can be purchased in a box, can, etc) and minimal animal or dairy products.
I don't think that is a strict diet, personally i eat the exact same thing everyday but that is because I am to lazy to create different foods and i enjoy what i do it.
Strictly adhereing to any diet restriction demands....which usually doesn't work for too long....because the key word is "restriction"
I don't like spicy food, after eat it the erythema will be found in my body, produce allergic reaction
Eating the exact same things every day.