The ketogenic diet involves a high intake of fat, moderate protein, and very low carbohydrates, shifting the body into ketosis. This metabolic state occurs when the body, deprived of glucose, breaks down fat into ketones for fuel. Individuals transitioning to this new pathway often report a temporary side effect known as “keto flu,” which frequently includes increased sweating, or hyperhidrosis. This temporary phase is a direct result of the metabolic and fluid shifts that occur as the body adapts to burning fat. The excessive heat and perspiration typically subside once the body becomes fully fat-adapted, usually within two to four weeks.
Metabolic Shift and Increased Body Heat
The transition from a carbohydrate-based metabolism to a fat-based one is a primary driver of temporary excessive sweating. When the body switches to using fat and ketones for energy, it activates thermogenesis, the production of heat within the body. This metabolic change leads to a temporary increase in core body temperature and, consequently, more sweating.
The mitochondria become more active in breaking down fat, a process that inherently generates heat as a byproduct. This elevated metabolic rate, sometimes called “keto thermogenesis,” represents the body efficiently utilizing stored fat. Furthermore, brown adipose tissue (BAT), which is specialized for heat generation, may have its activity modified by the ketogenic diet, contributing to the overall rise in internal temperature.
Another contributing factor is the excretion of acetone, one of the three main ketone bodies produced during fat metabolism. Acetone is a volatile compound the body expels through breath and, notably, through the skin, which increases the feeling of moisture and contributes to a distinct body odor. While adapting, the body may overproduce ketones, and the excess acetone eliminated through the skin can exacerbate the perception of increased perspiration.
Electrolyte Imbalance and Fluid Regulation
The rapid reduction in carbohydrate intake triggers a change in how the body manages water and essential minerals. Carbohydrates are stored as glycogen, and each gram is bound to approximately three to four grams of water. When intake is restricted, glycogen stores are quickly depleted, releasing this large volume of bound water, which is then eliminated through increased urination and sweating.
This initial water loss is compounded by hormonal changes related to insulin. Lower carbohydrate levels lead to decreased insulin production, and reduced insulin signals the kidneys to excrete more sodium and water. This natural diuretic effect means the body flushes out not just water but also essential electrolytes, including sodium, potassium, and magnesium.
The depletion of these minerals impairs the body’s ability to maintain fluid balance necessary for temperature regulation. When electrolyte levels are low, the body’s signaling pathways for hydration and heat dissipation are disrupted, causing the sweating response to become less controlled and more noticeable. The loss of sodium, in particular, makes it challenging for the body to retain the water needed to regulate temperature effectively.
Strategies for Managing Excessive Sweating
Since increased sweating is a symptom of metabolic and fluid shifts, management focuses on supporting the body through this transition. The body is losing water at an accelerated rate from the diet’s diuretic effect, so drinking plenty of water throughout the day helps mitigate dehydration and supports temperature control mechanisms.
Replenishment of lost minerals is necessary to address the electrolyte imbalance. Focus should be placed on consuming adequate sodium, potassium, and magnesium, often exceeding typical daily recommendations. For instance, a common recommendation is to aim for 3,000 to 5,000 milligrams of sodium daily, which can be achieved by adding salt to food or drinking mineral broths.
Wearing light, breathable fabrics, such as cotton or moisture-wicking materials, can help manage the physical discomfort of increased perspiration. Recognizing that this phase is temporary is also helpful, as the body typically becomes fully adapted to using fat for fuel within a few weeks, at which point the excessive sweating should diminish.