The problem is the less calories you consume, the less calories you expend as the body goes into ‘starvation mode’. Also, where is it getting the fuel from, muscle or fat?
Generally, if you eat the Standard American Diet - the one the US government approves of - then your energy comes from sugars. Carbs are just complex sugars that break down into simple sugars. So your body uses glucose for energy.
Some of us who eat carbs - I think it is largely based on how much sugar and simple carbs you ate as a kid - will get big blood sugar spikes and thus big spikes in insulin from eating carbs. The standard advice to eat lots of little meals results in lots of insulin spikes, so your body starts to tune out the insulin. Then your body starts producing MORE insulin as you become “insulin-resistant”. Taken far enough, insulin-resistance turns into diabetes.
I never became diabetic, probably because I DID diet multiple times a year and ran 30-40 miles a week.
But a good sign of insulin resistance is belly fat that just doesn’t go away. And insulin tends to put fat into long-term storage. So that when I lost weight down to 125, I was losing a lot of muscle and only some fat. And my body was fighting me because I was starving myself even though the fat was not being converted into energy - as it will for people who, for whatever reason, have bodies that are NOT insulin-resistant (such as my sister).
So my sister is OK with calories in/calories out. But it failed me because MY weight loss was as much muscle as fat. She also didn’t eat all the sugar and cookies that I ate as a young kid. Regardless, genetics or early eating habits, what works fine for her failed me for 50 years. What works for me now isn’t necessary for her.
When our hormones are right, our bodies regulate our weight. We WANT to eat less, or more, and our bodies respond correctly. But the enormous burst in gross obesity in the USA is due IMHO to the government preaching “low fat” - which then became “high sugar/high carb” - and a LOT of humans will respond by shifting into long-term fat storage. Not everyone, but a lot of us.
Those of us with that problem will then respond very well to restricting carbs. In my case, I need to STAY on a very low carb diet or I will start gaining weight back fast. Happily, I can live on a high fat, high protein, very low carb diet very easily. It isn’t a “diet” for me, but a lifestyle of eating differently from what many others do.
I’m doing time restricted eating too, between noon and 6 pm, but I think I’m moving to OMAD: One Meal A Day. I increasingly find I can eat one meal a day and not miss the other two or feel a need to snack. And if one eats one meal a day, it is TOUGH to eat enough in that one meal to get fat again!
Others will have different experiences and that is fine. Part of the US Government screwup was and is preaching we should all eat the same things the same way!
“The problem is the less calories you consume, the less calories you expend as the body goes into ‘starvation mode’. “
That’s the way it works for sedentary people.