Especially if weight loss is the end goal
Muscle loss is the main concern if protein is consistently low. The biggest problem with this is increased risk of injury during falls, and bone health long term is also compromised because of not having enough muscle to bear the physical load.
There is some theory coming up about muscle maintenance having a greater influence in other health factors too, but I’ve not read/learnt enough to explain that well
Amino acids play a large role in cellular health overall, not just muscle mass, including mental and sexual health… we don’t have to be too calculative in our consumption, but it helps to ensure every meal includes protein for a portion of it
In eating disorder/extreme cases, the body robs protein from muscles, including the heart. (See Karen Carpenter story) But anyone thoughtful enough to be looking into the question beforehand seems unlikely to fall into that category.
Proportionally your body will burn more muscle as a ratio to bodyfat.
When cutting your body must derive energy from its own mass.
Protein has a muscle sparing affect and a high intake will result in a better body composition come the end of your cut. Resistance training is equally important to preserve lean mass.
To simplify things just shoot for a gram per pound of body weight, you see sharply diminishing returns at higher intakes. For those in the other camp that suggest that level of protein intake is damaging, they are talking nonsense and do not have any compelling evidence for their claims.
As a side note, high protein intake is even more important cutting than bulking. Excess calories in themselves have a muscle sparing affect which you will not benefit from when cutting.
If you’re getting at least the minimum requirements and only missing out on optimal requirements you should be okay. The minimum recommended protein intake for me for example is 50g, but 75g is optimal for me for muscle growth. So I might not be getting 75g but unless I was much under 50g there would not likely be severe problems. If you’re concerned though you should talk to your doctor.
You lose weight. That’s mostly lean tissue. So your bmi goes down. And now you get to eat less food daily and your health gets worse.
You shouldn’t ever have a goal of losing weight. Your goal should be to lose fat.
Fats are essential to maintain healthy bodies, especially brain function. Protein is of course important but proper understanding of essential fatty acids are key for calorie restriction to balance with protein sources.