Calorie restriction can have mixed effects on the immune system in laboratory animals, sometimes improving responses to pathogen challenges and sometimes impairing immune function.

“uh so first of all laboratory uh animals in the laboratory are kept in in what's called a specific pathogen-free environment so that doesn't mean there's no pathogens but it's a relatively low pathogen in environment where they are not obligated to really use their immune systems against all the challenges that you know we would face in the real world so one question has come up uh are animals that are on calorie restriction immune compromise and again i think the data's a little bit mixed but certainly people have there have been studies where people have done pathogen challenges on cr animals and they respond better at least the old animals respond better than than age-matched ad libitum fed control so ad libitum just means eat as much as you want um but then for certain types of challenges they the caloric restriction clearly causes a deficit so yeah the sepsis experiments are pretty clear with the cr animals compared to controls when you induce sepsis in them the cr animals die much more quickly”