You've been sitting for twenty minutes, mid-fast, black coffee in hand. You stand up fast to grab a folder — and the room tilts for two seconds. Your instinct: "my blood sugar must be low." Except in most cases, that's not even it.
The real culprit: your body is dumping sodium, not just sugar
Within the first twelve to twenty-four hours of a fast, your body changes how it handles sodium at the kidney level. A hypothesis published in Frontiers in Endocrinology proposes a specific mechanism: in the proximal renal tubule, sodium and glucose get reabsorbed together through SGLT (sodium-glucose cotransporter) proteins, at roughly a one-to-one ratio. Less filtered glucose to reabsorb means mechanically less sodium retained along with it — and more sodium heading out in your urine. Researchers call this fasting-induced natriuresis, and it kicks in fast: as early as one overnight fast, with an almost immediate reversal (around 20 minutes) once you eat again.
This isn't a malfunction or a sign something's wrong — it's a documented renal mechanism, robust enough that it's being studied as a possible angle on treating hypertension in some patients. But for you, fasting and training, the practical consequence is simple: less circulating sodium means less plasma volume. Less plasma volume means less margin to compensate when you go from sitting to standing.
Why that turns into dizziness
When you stand, roughly 500 to 1,000 mL of blood shifts toward the lower body under gravity. Normally, baroreceptors detect the pressure drop and your nervous system compensates by speeding up the heart and constricting blood vessels. The problem shows up when circulating blood volume is already reduced at baseline — the system doesn't have the margin left to catch up in time. The clinical result has a name: orthostatic hypotension, defined as a systolic blood pressure drop of at least 20 mmHg (or diastolic drop of at least 10 mmHg) within three minutes of standing. Lightheadedness, blurred vision, and in more severe cases, syncope.
Dehydration and electrolyte disturbances — sodium and potassium chief among them — are among the most common non-neurogenic causes of this. An extended fast combined with training that has you sweating is exactly the setup that brings both together.
Where creatine fits in
A common belief says creatine "dries out" your blood by pulling water into muscle cells, which would make this worse. A study published in Medicine & Science in Sports & Exercise tested exactly that: creatine supplementation does increase total body water, but without altering the split between intracellular and extracellular compartments. In other words, plasma volume isn't siphoned off in favor of muscle — both increase together. That's not a guarantee against orthostatic dizziness, but it kills the myth that creatine is the culprit.
The move
Clinical guidance for volume-related orthostatic hypotension points to 2 to 3 grams of sodium per day plus adequate fluid intake to maintain plasma volume — not just plain water, which dilutes whatever sodium you've got left in circulation without replacing anything. Add potassium to that picture, since potassium deficiency is also among the documented causes.
That's exactly the problem we built Lyte & Loaded to solve: sodium and potassium at doses that reflect what your body is actually losing while fasted, paired with a creatine that doesn't work against it. Not a homeopathic trace on a marketing label — a formula built for someone fasting seriously and training fasted, not someone sipping a "detox" smoothie.
We didn't build Fasted Rebels to sell wellness. We built it because staying fasted and performing in training is a discipline, not an Instagram filter. Feed the mission. Not the hunger.
Sources: Frontiers in Endocrinology — "Fasting-Induced Natriuresis and SGLT: A New Hypothesis for an Old Enigma" (2020); American Family Physician — "Orthostatic Hypotension: A Practical Approach" (2022); PubMed/Medicine & Science in Sports & Exercise — "Creatine Supplementation Increases Total Body Water Without Altering Fluid Distribution" (Powers, Arnold et al.).
French version: Pourquoi tu as des vertiges en te levant pendant un jeûne
Also read, the fasting and electrolytes series: Why You're Cramping Mid-Fast · More Water While Fasted Isn't Always Safer · Why Your Heart Pounds Mid-Fast · Why You Twitch and Sleep Like Garbage Mid-Fast · Why You Get a Headache Mid-Fast · Why Your Uric Acid Spikes Mid-Fast · Why You're Always Cold Mid-Fast · Why Your Creatinine Spikes on a Blood Test · Do You Need Sugar to Get Creatine Into Your Muscles?