Using specific examples of a typical bodybuilding diet, I’m going to show you exactly why the experience of dieting down involves much more suffering than is necessary from a food enjoyment, satiety, and satiation perspective.
If you're a natural male lifter trying to diet down very lean (and this is assuming you have put on a good amount of overall muscle mass firts), chances are you will have to dip kcals down to sub 2k. Let's use 1800 kcals as an example. I'll set protein at 165 grams (1 gram per pound of LBM). Set fat at 50 grams. You're left with 690 kcals to play with in the form of carbs. If you're eating a reasonable and optimal 4 meals per day, you're likely going to cluster these carbs peri-workout. It'd probably look something like 300 kcals worth of carbs pre-workout and 300 kcals worth of carbs post-workout. When dieting hard in a deficit and carbs are low, you should have some carbs peri-workout. You don't necessarily need this many grams of carbs pre and post-workout but eating less than 300 kcals worth of the typical bodybuilding bro carb source is such a low volume of food that it's a tease and just leaves you feeling very deprived. Even so, when you're dieting hard, 300 kcals worth of even the typical bodybuilding bro carb source isn't all that satiating, even if you pair with a lean protein. And after those 2 meals, you're left with pretty much just protein and veggies for the other 2 meals—which sucks.
Let's use oatmeal as an example. 300 kcals of oatmeal is 80 grams of dry oats which is 1 cup. You prepare with 1.75 cups of water which is 414 grams. You pair with a lean protein source, likely 150-200 grams worth. At most, you're looking at 690 grams for the whole meal. This is for a meal that clocks in at around 500 kcals. Oatmeal is already lacking in texture (baby food texture), so you won't enjoy it that much. So you're likely not going to add even more water.
Let's compare this to 32 grams of puffed kamut + 800 cc cold water + 4 grams TN chocolate flavor pack + 161 grams chicken breast. That is about 1,000 grams for the whole meal. 1,000 grams for 300 kcals. Way more satiating and crosses that 800-900 gram threshold. And if I eat this meal both pre and post-workout, out of the 690 kcals worth of carbs I can play with for the day, I still have 490 kcals left to play with for my other 2 meals. Hell, I could do puffed kamut AGAIN for those last 2 meals and STILL have 290 kcals left of carbs to play with.
I'm not really going to cover cream of rice, white rice, brown rice, bread, pasta. They are even worse from a satiety and satiation aspect compared to oatmeal.
I already talked about why puffed products are very suboptimal choices. Air doesn't make it into your stomach. And 300 kcals of something like Quaker Rice Cakes is only 78 grams of food.
Fruits and veggies. Let's use broccoli and strawberries as examples. 100 kcals of broccoli is 300 grams. 100 kcals of strawberries is 300 grams. My puffed kamut concoction is 113 kcals and 836 grams. Further, I don't know about you but my palate gets pretty bored after eating 100 kcals worth of strawberries, blueberries, broccoli, cauliflower, etc.—even if I haven't achieved satiation yet. At the very least, it would prefer to have a starchy carb source (e.g. puffed kamut). If volume was the only thing that mattered for satiation, then we could just chug liquids. Unfortunately, that's not the case. It's hard to override that innate desire to actually experience chewing and swallowing starchy carbs.
Protein ice cream. This is actually not a bad option from a volume standpoint. However— and this is really getting into personal preference—my reasoning for not really eating protein ice cream on low days is while I do like sweets, I also have a craving for savory foods. Veggies don't really cut it for me. It is very difficult to find or put together high volume savory carb sources. So I tend to like to keep my protein sources in my 4 meals savory (egg whites + whole eggs, chicken breast, beef, salmon). Keeping your protein sources savory allows you to capitalize on the IMG + MSG umami synergy that increases satiety. I am satiated for much longer with a puffed kamut + wild salmon meal compared to a protein ice cream meal even when kcals are controlled for.
Pay attention to your cravings, satiation, and satiety. Pay attention to them before, during, and after meals. Like for me I typically crave both sweet and savory in a meal—which is why puffed kamut (with 800 cc cold water + TN chocolate flavor pack) and a savory protein source work so well. Even if I were able to reach the point of satiation volume wise, if the meal only consisted savory foods or only consisted of sweet foods, my cravings would still be there; and I would be quite hungry very soon after the meal.
Intermittent fasting. If you eat less than 4 evenly spaced out meals per day, it's suboptimal from a protein bolus frequency standpoint for maximizing hypertrophy/LBM retention. If you make 1-3 of those meals just protein, it's just a tease. Is it worth it to suffer for those 1-3 meals or to just be hungry the majority of the day so you can have 1-2 large meals per day where you actually achieve satiation? YMMV, but not for me. I'd rather be satiated all 4 meals of the day—pretty much throughout the entire day.
Also, many of the most productive people I know train in the AM shortly after waking up. Acknowledging you should have carbs and protein around your workout, with intermittent fasting are you really going to structure your day so that you're not going to eat or only have protein meals the rest of the day? It significantly constrains your options if you eat out at night as well—and social gatherings involving food are typically going to take place at night. With the way I have my diet set up, I am not only satiated but I have also only consumed ~1100 kcals by the time my last meal comes around, which gives me a lot of leeway/freedom to eat out at night.
Keto products. How many calories your body digests and absorbs from these products will vary. Take the kcal values on the nutrition labels with a huge grain of salt. Whenever I incorporate products like these into my diet, my BW responds in a way that suggests I’m eating more than my logged kcal intake. For example, if 1800 kcals puts me in a mild deficit, just subbing in 1 pint of “240 kcal” Nick’s Ice Cream (total kcals for the day tallying up to 1800 kcals) will take me out of that deficit and result in BW stall. I’ve experienced the same with other keto products like Aunt Millie’s bread and Quest bars.