Based on my personal experience, whether you exercise or not you are still going to be miserable when on caloric restriction.
But when you are exercising your portions do not get so small. In fact, you could be eating exactly the same and if you add walking about 10km (6 miles) every day, you are putting yourself in a significant calorie deficit of about 600 kcal (adult male, regular height, a bit overweight).
While it does not matter where 600kcal deficit comes from from thermodynamic point of view, it makes dieting easier:
* The food portions have the size you are used to. Your stomach is used to about this kind of food. At least some satiety signals are going to be the same as before you started dieting.
* Exercising will preserve muscle mass. We have a mechanism where if the body needs to access stored energy it will spare the muscles that are being exercised. This is how bodybuilders are cutting -- during cutting phase they are reducing their fat without building new muscle but are still exercising. This exercising is necessary so that the body burns fat preferentially rather than going for muscle protein.
* Exercising seems to prevent most or all of BMR drop from calorie restriction. Normally, if you just reduce your calories without much activity, the body will start conserving energy in various ways (for example I felt cold on hot days which was super interesting feeling). If BMR drops, you need to reduce your food intake even further to ensure the same level of calorie restriction. And if you do not do this you might find that a) you have reduced your calorie intake and b) you are not losing weight. Terrible place to be in. Activity prevents that from happening.
Your points are all valid, you've perhaps convinced me to give it a go again. Only thing I'd add is walking for 2 hours in total a day every single day is hardly feasible.
I just checked my Garmin progress reports. In April I injured my foot and could not run but could walk and so while I was recovering I started walking a lot to replace and later supplement my running.
Over the period of six month from May 2023 to October 2023 I logged:
* 2497km of combined walks and runs (about 80% walks and running the rest), about 13.6km a day on average
* 384h of activities (for about 2h 7m daily average)
* about 6.5km/h average activity speed. I walk at about 6km/h normally (sometimes faster, sometimes slower), some of the activity time is probably walking into groceries or standing in a queue for a coffee and some of the activities are runs.
* 709k steps in May
* 775k steps in June
* 792k steps in July
* 808k steps in August
* 713k steps in September
* 618k steps in October
For a total of 4.4M steps in 6 months or about 24.2k steps a day, on average.
* as an interesting note, Garmin estimates that my activities burned 180 thousand kcalories which translates to 20kg of pure fat or about 23kg of adipose tissue (I have maintained my weight during that period, though). Hard to say how accurate this is.
So, yes, it is feasible. Though quite time consuming. I switched my entertainment needs to consuming audiobooks and whatever informational/educational content I could put my hands on that would be even remotely useful.
Based on my personal experience, whether you exercise or not you are still going to be miserable when on caloric restriction.
But when you are exercising your portions do not get so small. In fact, you could be eating exactly the same and if you add walking about 10km (6 miles) every day, you are putting yourself in a significant calorie deficit of about 600 kcal (adult male, regular height, a bit overweight).
While it does not matter where 600kcal deficit comes from from thermodynamic point of view, it makes dieting easier:
* The food portions have the size you are used to. Your stomach is used to about this kind of food. At least some satiety signals are going to be the same as before you started dieting.
* Exercising will preserve muscle mass. We have a mechanism where if the body needs to access stored energy it will spare the muscles that are being exercised. This is how bodybuilders are cutting -- during cutting phase they are reducing their fat without building new muscle but are still exercising. This exercising is necessary so that the body burns fat preferentially rather than going for muscle protein.
* Exercising seems to prevent most or all of BMR drop from calorie restriction. Normally, if you just reduce your calories without much activity, the body will start conserving energy in various ways (for example I felt cold on hot days which was super interesting feeling). If BMR drops, you need to reduce your food intake even further to ensure the same level of calorie restriction. And if you do not do this you might find that a) you have reduced your calorie intake and b) you are not losing weight. Terrible place to be in. Activity prevents that from happening.