Malnutrition is about lacking essential nutrients. Fasting is very different than "eating less".
The body works in one of two mode. 1: use current energy, as long as you provide energy (eating) it'll use it and make you hungry if you're not giving it enough. 2: use stored energy. If you stop eating for long enough (some say 12 hours, other say 24 hours, I suspect it depends on what you have make your body used to, eg some long distance runners fast to make their body switch to fat burning mode earlier). The body has zero energy available in stomach/muscles, it'll then start burning stored fat ; unless you're very skinny, you can go on stored fat for a long time.
If you eat normal meals (no calorie restriction, you shouldn't be hungry at the end of the meal) between fasts, it shouldn't lead to health problems.
Recent studies show that the refeeding at the end of a 5+ day fast is benefic for your health, the closest thing to stem cells. Google "Valter Longo" for more information about it.
For general information about fasting, check Jason Fung material (blogs, youtube). He's a medical doctor who runs a clinic to cure patients of diabetes type 2 through fasting, and has put out a lot of material out there with lots of explanations.
The body works in one of two mode. 1: use current energy, as long as you provide energy (eating) it'll use it and make you hungry if you're not giving it enough. 2: use stored energy. If you stop eating for long enough (some say 12 hours, other say 24 hours, I suspect it depends on what you have make your body used to, eg some long distance runners fast to make their body switch to fat burning mode earlier). The body has zero energy available in stomach/muscles, it'll then start burning stored fat ; unless you're very skinny, you can go on stored fat for a long time.
If you eat normal meals (no calorie restriction, you shouldn't be hungry at the end of the meal) between fasts, it shouldn't lead to health problems.
Recent studies show that the refeeding at the end of a 5+ day fast is benefic for your health, the closest thing to stem cells. Google "Valter Longo" for more information about it.
For general information about fasting, check Jason Fung material (blogs, youtube). He's a medical doctor who runs a clinic to cure patients of diabetes type 2 through fasting, and has put out a lot of material out there with lots of explanations.