Electrolytes first — the 'keto flu'
When carbs drop, insulin falls and the kidneys excrete more sodium and water, pulling potassium and magnesium along — the cause of the early 'keto flu' (fatigue, headache, cramps). Replacing sodium (often the biggest need), plus adequate magnesium and potassium, prevents most of it [1][2]. Get potassium mainly from low-carb vegetables; be cautious with potassium supplements if you have kidney issues or take certain medications [2].
Fiber and digestion
Low-carb diets can be low in fiber, causing constipation. Psyllium husk (and low-carb vegetables) supports regularity with minimal digestible carbs [3].
Filling common gaps
- Vitamin D and omega-3s are sensible if your intake is low, as on any diet.
- A low-carb diet can still be nutrient-dense, so whole foods come first.
MCT oil and exogenous ketones — temper expectations
- MCT oil is a rapidly used fat that can raise ketones modestly and is a convenient fuel; it is not a fat-loss shortcut, and too much causes GI upset.
- Exogenous ketone supplements raise blood ketones briefly but don't replicate the metabolic state of dietary ketosis or drive fat loss — largely overhyped.
Practical guidance
Prioritize sodium, magnesium, and potassium to prevent the keto flu (food-first for potassium); add psyllium for fiber; cover vitamin D and omega-3 gaps; use MCT oil as an optional fuel with modest expectations; skip exogenous ketones; and involve a clinician if you have diabetes, kidney issues, or take medications.
