Supplementation

This content is for informational purposes only and does not constitute medical or nutritional advice. Speak with your health professional before starting this protocol.

Supplement disclaimer: The supplements listed here are necessary safety components of this protocol, not optional additions. Some interact with prescription medications — particularly anticoagulants, thyroid medications, and immunosuppressants. If you take any prescription drugs, check with your pharmacist or health professional before starting supplementation.

Supplementation is a core safety component of the FLS protocol, not an optional extra.

When food intake drops to the levels prescribed by this protocol, it becomes impossible to obtain adequate micronutrients from food alone. The supplements in this chapter address the specific gaps created by severe caloric restriction and prevent the complications that historically plagued unsupervised VLCDs.

The protocol calls for all listed supplements to be taken daily throughout the sprint.

Required Supplements

1. Sodium (Salt)

Why you need it: Severe carbohydrate restriction drops insulin levels. Insulin normally signals the kidneys to retain sodium. Without it, your kidneys excrete sodium rapidly. This sodium loss is responsible for much of the water weight loss in week one, and causes the headache, dizziness, fatigue, and muscle cramps often called "keto flu" (Phinney, 2004).

Target: 2,000–3,000 mg of additional sodium per day, on top of what is in your food.

How to get it:

Table salt (sodium chloride): approximately 2,300 mg sodium per teaspoon
Bouillon or broth: 1–2 cups per day
Salt added liberally to meals

If you experience headache, dizziness, or fatigue in the first week, increase sodium first. These symptoms are almost always sodium depletion, not calorie deprivation.

2. Potassium

Why you need it: Potassium is the most critical electrolyte for cardiac safety during your sprint. The cardiac deaths associated with 1970s liquid protein diets were caused primarily by potassium depletion and resulting arrhythmias (Isner et al., 1979). Increased renal sodium excretion carries potassium with it; low food intake provides insufficient dietary potassium. The combination is dangerous if you do not replace what you lose.

Target: 1,000–3,000 mg per day total (food plus supplement combined).

Food first. Most users hit the target from greens plus a salt substitute on meals — no capsule needed. OTC potassium capsules cap at ~99 mg per tablet (FDA rule), so pills are a top-up, not the main vehicle. You would need ten or more capsules a day to replace what a single serving of greens already provides.

How to get it (in order of practical priority):

Food first — the easiest and cheapest way:
- Cooked spinach: ~420 mg per cup
- Avocado: ~485 mg per half
- Mushrooms: ~356 mg per cup
- Potato (refeed days): ~610 mg per medium
- Tomato: ~290 mg per medium
- Two cups of mixed cooked greens already lands you in the 1,500–2,500 mg range — right inside the target.
Salt substitute on meals (the easiest "supplement"):
- Potassium chloride blends: LoSalt, NoSalt, Nu-Salt, lite-salt — all ~650 mg per ¼ teaspoon. Sprinkle on meals when greens are light that day.
Sugar-free electrolyte drinks containing potassium — useful around training.
Potassium citrate or gluconate capsules — only as a top-up if food + salt substitute fall short. Remember the 99 mg/tablet cap.

Caution: If you are on potassium-sparing diuretics, ACE inhibitors, or ARBs, consult your health professional before supplementing potassium. These medications can cause potassium retention and dangerous hyperkalemia.

3. Magnesium

Why you need it: Magnesium participates in over 300 enzymatic reactions. Deficiency during caloric restriction causes muscle cramps, sleep disruption, anxiety, and cardiac arrhythmias (Gröber et al., 2015).

Target: 200–400 mg of elemental magnesium per day.

Recommended forms (in order of preference):

Magnesium glycinate: best absorbed, least GI distress
Magnesium citrate: well absorbed, may cause loose stools at higher doses
Magnesium taurate: good for cardiovascular support
Avoid magnesium oxide: poorly absorbed

The protocol recommends taking magnesium before bed, as it may improve sleep quality during the sprint.

4. Comprehensive Multivitamin

Why you need it: Your sprint diet cannot provide adequate amounts of all essential vitamins and minerals. A quality multivitamin fills the gaps (Fairfield & Fletcher, 2002).

Target: One high-quality multivitamin per day, taken with a meal.

What to look for:

At least 100% of the RDI for vitamins A, C, D, E, K, B-complex vitamins, zinc, selenium, and copper
Third-party tested (NSF, USP, or Informed Sport certified)
No megadoses of individual nutrients

5. Calcium

Why you need it: Dietary calcium is difficult to obtain in adequate amounts during a Fat Loss Sprint, particularly with limited dairy intake. Adequate calcium is essential for bone health, muscle contraction, and nerve function. Sustained caloric restriction without adequate calcium intake risks bone mineral density loss (Villareal et al., 2006).

Target: 500–1,000 mg per day from food and supplements combined.

Forms:

Calcium citrate: better absorbed on an empty stomach
Calcium carbonate: take with meals for best absorption

6. Vitamin D3

Why you need it: Vitamin D deficiency is common in the general population and worsens during caloric restriction. Deficiency is linked to immune dysfunction, low mood, and metabolic impairment. Vitamin D also drives calcium absorption, making it essential alongside your calcium supplement (Holick, 2007).

Target: 2,000–4,000 IU (50–100 µg) per day.

The protocol recommends taking vitamin D with a meal that contains fat. Vitamin D is fat-soluble, and even the small amount of fat in a sprint meal is sufficient for absorption.

7. Fish Oil (EPA and DHA)

Why you need it: Fish oil provides EPA and DHA, two long-chain omega-3 fatty acids that serve multiple functions during your sprint (Calder, 2015):

Anti-inflammatory: EPA and DHA are precursors to resolvins and protectins, which actively resolve inflammation
Lean mass support: some evidence suggests omega-3 supplementation enhances the anabolic response to protein intake and may support lean mass preservation during caloric restriction (Smith et al., 2011)
Cardiovascular protection: EPA and DHA reduce triglycerides and may reduce cardiac arrhythmia risk
Mood support: DHA is a structural component of brain tissue; supplementation may support mood stability during restriction

Target: 2–3 g of combined EPA+DHA per day. This typically requires 4–6 standard fish oil capsules or 1–2 concentrated omega-3 capsules.

Note: Fish oil contains approximately 9 kcal per gram. At 3 g, it adds roughly 27 kcal, accounted for within your fat allowance.

Recommended Supplements (Evidence-Supported, Optional)

8. Psyllium Husk (Fibre)

Reduced food volume during your sprint can cause constipation. Psyllium husk is a soluble fibre that absorbs water, increases stool bulk, and promotes regularity. It also adds to satiety (Slavin, 2005).

Target: 5–10 g per day. Start at 5 g and increase if needed.

The protocol recommends mixing psyllium with water and drinking immediately, as it gels quickly. Take with at least 250 ml of water, and between meals rather than alongside protein meals, as it can slow protein absorption.

9. Caffeine

Caffeine provides real benefits during a sprint:

Appetite suppression
Increased energy and alertness during caloric restriction
Mild thermogenic effect: approximately 3–5% increase in energy expenditure
Enhanced fat oxidation (Acheson et al., 2004)

Target: 100–400 mg per day (roughly 1–4 cups of coffee or equivalent).

The protocol recommends avoiding caffeine after 2:00 PM to protect sleep quality. If you are caffeine-sensitive, starting at the lower end of the range is advisable.

10. Creatine Monohydrate

Creatine supports phosphocreatine resynthesis during resistance training and may help maintain training performance despite the caloric deficit. Evidence for lean mass preservation during caloric restriction is mixed but favorable (Antonio et al., 2021).

Target: 3–5 g per day. No loading phase needed.

Note: Creatine causes water retention within muscle tissue, typically 1–2 kg. This shows on the scale but does not represent fat gain. If scale weight is your primary progress metric during the sprint, you may prefer to add creatine during your maintenance phase instead.

Full Supplement Protocol at a Glance

Supplement	Daily Target	Timing	Priority
Sodium	2,000–3,000 mg added	Throughout the day; broth recommended	Required
Potassium	1,000–3,000 mg total	Food first; salt substitute on meals; capsules only as top-up	Required
Magnesium (glycinate or citrate)	200–400 mg elemental	Before bed	Required
Multivitamin	1 per day	With a meal	Required
Calcium (citrate or carbonate)	500–1,000 mg	With meals	Required
Vitamin D3	2,000–4,000 IU	With a meal containing fat	Required
Fish oil (EPA+DHA combined)	2–3 g	With meals, divided	Required
Psyllium husk	5–10 g	Between meals, with water	Recommended
Caffeine	100–400 mg	Morning or early afternoon	Optional
Creatine monohydrate	3–5 g	Any time	Optional

What to Avoid

Fat burners and thermogenics: These typically contain stimulants like synephrine or yohimbine that raise heart rate and blood pressure. They are unnecessary and potentially dangerous during severe caloric restriction.

BCAAs: If your protein intake meets your target, BCAAs provide no additional benefit. They are a subset of the amino acids you are already consuming in adequate quantities.

Diuretics: Dangerous during a protocol that already promotes fluid loss. Can cause severe electrolyte imbalances.

Unsupervised appetite suppressants: Do not self-administer pharmaceutical appetite-suppressing medications unless prescribed and supervised by a physician.

Key Takeaways

The protocol includes all listed supplements throughout the sprint. Severe caloric restriction creates micronutrient gaps that food alone cannot fill.
Electrolytes (sodium, potassium, magnesium) are the most critical safety measures. They prevent the cardiac and neuromuscular complications that historically occurred in unsupervised VLCDs.
If you experience headaches, dizziness, or cramps in the first week, increase sodium immediately.
Fish oil, vitamin D, calcium, and a multivitamin cover your micronutrient and essential fat requirements.
Psyllium husk and caffeine are valuable additions. Creatine is optional and may affect scale readings.
Avoid fat burners, BCAAs, diuretics, and unsupervised appetite suppressants.

References

Acheson, K. J., et al. (2004). The American Journal of Clinical Nutrition, 33(5), 989–997. https://doi.org/10.1093/ajcn/33.5.989

Antonio, J., et al. (2021). Journal of the International Society of Sports Nutrition, 18(1), 13. https://doi.org/10.1186/s12970-021-00412-w

Calder, P. C. (2015). JPEN, 39(S1), 18S–32S. https://doi.org/10.1177/0148607115595980

Fairfield, K. M., & Fletcher, R. H. (2002). JAMA, 287(23), 3116–3126. https://doi.org/10.1001/jama.287.23.3116

Gröber, U., Schmidt, J., & Kisters, K. (2015). Nutrients, 7(9), 8199–8226. https://doi.org/10.3390/nu7095388

Holick, M. F. (2007). New England Journal of Medicine, 357(3), 266–281. https://doi.org/10.1056/NEJMra070553

Isner, J. M., et al. (1979). Circulation, 60(6), 1401–1412. https://doi.org/10.1161/01.CIR.60.6.1401

Phinney, S. D. (2004). Nutrition and Metabolism, 1(1), 2. https://doi.org/10.1186/1743-7075-1-2

Slavin, J. (2005). Nutrition, 21(3), 411–418. https://doi.org/10.1016/j.nut.2004.08.018

Smith, G. I., et al. (2011). Clinical Science, 121(6), 267–278. https://doi.org/10.1042/CS20100597

Villareal, D. T., et al. (2006). Archives of Internal Medicine, 166(22), 2502–2510. https://doi.org/10.1001/archinte.166.22.2502