Some people experience various temporary side effects when converting to a Low Carb, High Fat diet. This is a result of your body switching from using carbohydrates as its primary fuel source to using fat as a fuel. For most of these people the side effects tend to be mild and do not last longer than a week.
Foods that are high in carbohydrates increase water retention in your body. When you stop eating these foods the excess water is excreted through the kidneys and the body can become mildly dehydrated and deficient in salts. The physical effects of this in the short term may include headaches, dizziness, shivers, sweats, cramping, irritability, heart palpitations, muscle pain and fatigue. These complaints can be minimised by increasing your intake of fluids and your salt intake. Drinking more water, adding salt to your food and drinking bone broth will aid in the transition period.