You absolutely
do need to eat a certain amount of calories to lose weight and to stay healthy.
Some key points from the article below (there are also many other articles and studies from credible sources that say the same things):
Extremely low-calorie diets trigger metabolic adaptation, forcing the body to slow its metabolism and conserve energy, which causes a weight-loss plateau. Additionally, this can lead to muscle loss, severe fatigue, increased cravings, and hormonal imbalances, making it harder to sustain long-term weight loss.~
Eating too little doesn’t speed up fat loss but it slows it down. Your metabolism needs energy to function well, and nourishment is the key to sustainable progress. Check out more information in this article.
www.weightkidneycare.com
I do not believe there is credible science to support the idea that a lower calorie deficit can cause more weight loss. There have been a lot of studies done over decades that included measurements of actual energy expenditure, and in general the numbers do always add up.
I think the main reason CICO can look like it is not making sense is not adequately accounting for alterations in energy expenditure secondary to weight loss, and people being terribly inaccurate at calorie counting. So it is possible to not lose weight on fairly low daily calorie intake in that post weight loss state ( that may last forever ) , but I have seen no evidence that increasing intake will cause weight loss in that state.
A severe calorie deficit causing very rapid weight loss can definitely cause problems. The most obvious ones being faintness, actual fainting, tiredness, exhaustion, electrolyte imbalances, and higher rates of gallstones. So losing weight super fast can have negative health consequences.
When weight is lost energy expenditure drops for 3 reasons , one is that the no longer there fat and lean tissue no longer consumes any calories, and this may be a large effect if a lot of weight is lost. The second reason is it takes less energy to move a body that weighs less, not sure how significant this is in reality, but logically it must happen . The third is reduced energy expenditure from the body's attempt to conserve energy and or fat stores. I believe that the metabolic adaptation to low calorie input is more dependent on time, and total weight lost , rather than how low the calorie intake is.
When I started at 145 kg , without GLP drugs at that point, I ate 1600-1800 kcal per day, was very inactive, and lost 6kg per month consistently until I got to about 90 kg so in about 9 months or so, weight loss then slowed slowly but surely to zero over the next several months with no change in calorie intake and stopped at 75 kg , where it stayed for a year or so, until I started taking ozempic, and it still stayed there for another year, all with the same calorie intake.
This enormous effect on energy expenditure did not require extreme calorie deficits, occurring at a calorie intake exactly the same as what was required to maintain the weight loss.
Maintaining weight loss is extremely difficult, the low energy expenditure combined with the increased hunger from massive weight loss, made me pretty hungry most of the time despite a diet designed to minimise hunger - very high protein 40-50% of calories, low calorific density , total avoidance of high calorific density / highly rewarding / high glycaemic index foods. This is the exact problem that makes long term weight loss nearly impossible, but it does not require extra low calorie intake to get there, just weight loss , and possibly time of low calorie input. Thankfully GLP drugs help with hunger so hopefully maintaining that weight loss will be possible
