Very-Low-Carbohydrate Diet, GLP-1 Therapy, and Mid-Workout Dizziness

The honest answer is that hypoglycemia is possible but not the most likely explanation, and a coach who jumps straight to "it's low blood sugar" may miss something. Metformin alone rarely causes hypoglycemia; semaglutide adds appetite suppression and delayed gastric emptying but is not itself a strong hypoglycemic agent. What makes Marcus high-risk is the stacking: total intake near 1,400 kcal, carbohydrate under 30 g/day, glycogen depletion, unaccustomed treadmill work, and a GLP-1 agent that suppresses thirst and intake.

More plausible contributors to his symptoms:

• Volume and sodium depletion. Low carbohydrate intake drives natriuresis and glycogen-bound water loss (the 2.5 kg is largely water). Combined with lisinopril, this can produce orthostatic hypotension - light-headedness that peaks on standing or mid-exercise.
• Under-fueling before training: 1,400 kcal/day against a 101 kg body weight is a steep deficit on top of a drug that blunts hunger.
• GI effects of semaglutide (loose stools) worsening dehydration and electrolyte loss.

First action: do not reassure, do not adjust medication, and do not simply "add carbs." Document the episodes (timing, duration, relation to meals and sessions), ask whether he has a glucose meter and what it read during an episode, and refer to his physician with a written summary. In the interim, remove fasted and un-fueled training sessions and have him train after a meal containing carbohydrate and protein. Frame this as risk management, not as abandoning his goal.

For an adult in an energy deficit doing resistance training, the evidence supports roughly 1.2–1.6 g/kg/day to preserve lean mass; higher intakes are not clearly harmful but offer diminishing returns.

The choice of denominator matters more than the exact multiplier. Using actual body weight (101 kg) at 1.6 g/kg gives 162 g/day - about 650 kcal of protein out of a 1,400 kcal intake, which crowds out the carbohydrate and fat he needs and is not required to protect lean mass. In clients with obesity, practitioners commonly use an adjusted or reference weight.

Worked calculation:

• Devine ideal body weight for a 1.75 m male ≈ 50 + 2.3 × (68.9 in − 60) ≈ 70.5 kg.
• Adjusted body weight = IBW + 0.4 × (actual − IBW) = 70.5 + 0.4 × 30.5 ≈ 82.7 kg.
• 1.2–1.6 g/kg × 82.7 kg ≈ 99–132 g protein/day, so target ~110–120 g.

Practical framing: distribute over three to four feedings of 25–40 g, prioritize at breakfast (typically the weakest meal), and choose sources he tolerates given the delayed gastric emptying - Greek yogurt, eggs, fish, poultry, and a whey or plant supplement if solid food volume is a problem. Revisit the target if his physician changes his medication or if his intake rises; the number is a starting point, not a verdict.

Say it plainly and warmly, in one short paragraph, then redirect to what you can do. Something like: "I'm glad the diet is doing something you can see, and I want that to continue safely. Tapering metformin is a medical decision - I'm not licensed to make it and neither of us should test it by experiment. What I can do is get you to your physician with a clear summary of what's changed, and make sure your training and eating support whatever they decide."

What I will not do:

• Recommend, time, or adjust any dose of metformin, semaglutide, or lisinopril.
• Interpret his glucose readings as a diagnosis or tell him a reading means he can skip a dose.
• Endorse the framing that a diet "reverses" diabetes; improvement in glycemic control is a real and worthwhile outcome, but it is his physician's call how to describe and manage it.

What I will do:

• Prepare a one-page summary for his physician: symptom log, training schedule, estimated intake, weight change, and that he is requesting a medication review.
• Ask his physician (with Marcus's written permission) what glucose monitoring and symptom thresholds should trigger a call.
• Keep coaching the parts that are mine: meal timing around training, protein distribution, hydration and sodium, and adherence.
• Document the referral and the conversation in his file the same day.

This protects Marcus clinically and protects you professionally - a client who believes a coach co-signed a medication change is a liability and a health risk.