The low-carb diet is one that absolutely requires more sodium. A lot more sodium. If you've got the brutal headaches that some people get In some cases, low carb diets may cause diarrhea, constipation and headaches. They may cause lower mental acuity. The brain needs glucose to function To Treat and Prevent Low Carb Diet Headaches. Strict "no carb" phases of low carb diets have developed a reputation for giving dieters severe headaches....