Obese lost 17 lbs in 3 months with diet and just 3 doses of semi-acivated vitamin D
Cholecalciferol vs. calcifediol supplementation on visceral adiposity in people with obesity: a real-world retrospective study
Front. Nutr., 18 November 2025 Volume 12 - 2025 https://doi.org/10.3389/fnut.2025.1676668 Italy
Introduction: Nowadays it is well known that obesity and vitamin D deficiency are closely linked. In this view, this study aimed to assess the effects of two different Vitamin D formulations, combined with a Mediterranean hypocaloric diet (MHD) on 25(OH)D concentration, weight loss and visceral adiposity in subjects with obesity and vitamin D insufficiency/deficiency.
Methods: Eighty-four patients with obesity were retrospectively selected and divided into three groups according to the type of treatment received: MHD alone (C group), MHD + cholecalciferol (D group), and MHD + calcifediol (N group). 25(OH)D concentration, anthropometric parameters, body composition and visceral adiposity indices (LAP, VAI, NVAI) were assessed at baseline and after 3 months.
Results: All groups showed significant reductions in anthropometric parameters after 3 months. Notably, Group N achieved the greatest increase in serum 25(OH)D (+20 ng/mL), the highest weight loss (−7.8 Kg) and a significant improvement in LAP and NVAI. In addition, only N group showed an increased fat-free mass. Regression analysis confirmed a significant association between calcifediol treatment and LAP reduction, independent of BMI.
Discussion: Calcifediol supplementation, combined with a MHD, is more effective than cholecalciferol in improving vitamin D status and reducing visceral adiposity in subjects with obesity. These findings support the recommended use of calcifediol supplementation in obesity-related vitamin D deficiency management.
"Participants in the D group received a monthly dose of 25,000 IU of cholecalciferol for 3 months, while those in the N group were treated with 0.266 mg/monthly of calcifediol for the same duration. "
"Monthly supplementation was also chosen to ensure better adherence compared to daily or weekly administration."
Chart from PDF: Weight in kilograms, Vitamin D in nanograms/mL
- Getting Vitamin D into your blood and cells Notice: Calcidiol IS NOT stored in the fat
600 micrograms of Calcifediol costs $16 on Amazon 60 pills of 10 mcg
Comment on the study
This was explicitly described as a “real‑world retrospective study,” not a randomized, blinded trial.
The groups were defined after the fact based on which treatment patients had actually received in routine care (diet only, diet + cholecalciferol, or diet + calcifediol), so there was no placebo arm and no indication of blinding of patients or clinicians regarding the form of vitamin D
Asked Perplexity AI: Can a person lose more weight on a diet if they take Calcidiol than if they take the same amount of vitamin D?
Recent clinical findings, specifically from research published in late 2025, indicate that taking Calcidiol (Calcifediol) can lead to significantly more weight loss than taking standard Vitamin D3 (cholecalciferol) when combined with a diet.
While standard Vitamin D supplements often fail to produce measurable weight loss in clinical trials, Calcidiol appears to bypass specific metabolic roadblocks present in overweight individuals.
Executive Summary: The Core Advantage
- Efficacy: In a comparative study of obese patients on a hypocaloric diet, those taking Calcidiol lost significantly more weight (-7.8 kg) compared to those taking standard Vitamin D3, who lost less weight or showed no significant difference from placebo.1
- Mechanism: Standard Vitamin D gets "trapped" in body fat, making it less effective for overweight people. Calcidiol is less fat-soluble and enters the bloodstream directly, correcting deficiency 3x faster and more effectively.2 3
- Availability: Unlike standard Vitamin D3 (available everywhere cheaply), Calcidiol is often a prescription medication (e.g., Rayaldee) or a specialized, more expensive supplement (e.g., d.velop).4 5
1. The Evidence: Calcidiol vs. Vitamin D3
For years, studies on standard Vitamin D3 and weight loss were disappointing. While low Vitamin D levels are linked to obesity, taking standard pills rarely caused weight loss. However, new evidence suggests the form of the vitamin matters.
Key Study (2025)
A retrospective study titled "Cholecalciferol vs. calcifediol supplementation on visceral adiposity in people with obesity" compared three groups of patients on a Mediterranean hypocaloric diet:
- Group 1 (Diet only): Lost some weight.
- Group 2 (Diet + Vitamin D3): Improved Vitamin D levels slightly but had less impact on weight.
- Group 3 (Diet + Calcidiol): Achieved the highest weight loss (-7.8 kg), the greatest reduction in visceral (belly) fat, and the fastest increase in serum Vitamin D levels.1
Why Vitamin D3 Often Fails
Standard Vitamin D3 (cholecalciferol) is fat-soluble. When an overweight person takes it, the vitamin is quickly sequestered (trapped) in adipose tissue (body fat) before the liver can convert it into the active form the body uses. This explains why obese individuals often need 2–3x higher doses of Vitamin D3 to achieve the same blood levels as lean individuals.6
2. The Biological Mechanism: Bypassing the "Fat Trap"
Calcidiol is chemically different from Vitamin D3. It is 25-hydroxyvitamin D—the exact molecule your liver creates after it processes Vitamin D3. Taking it directly offers two advantages for weight loss:
| Feature | Standard Vitamin D3 (Cholecalciferol) | Calcidiol (Calcifediol) |
|---|---|---|
| Solubility | Highly Fat-Soluble (Lipophilic) | More Water-Soluble (Hydrophilic) |
| Absorption | Gets trapped in body fat stores. | Bypasses fat storage; stays in blood. |
| Conversion | Needs liver processing (CYP2R1 enzyme). | No liver processing needed. |
| Potency | Takes months to raise levels. | Raises levels in days/weeks (~3x potent). |
| Weight Effect | often negligible in trials. | Linked to greater fat loss \& metabolic improvement. |
The "Liver Block": Obesity can downregulate the liver enzyme (CYP2R1) needed to process standard Vitamin D3. Because Calcidiol skips this step, it works effectively even in people with "sluggish" Vitamin D metabolism.6
3. Availability and Cost
While Vitamin D3 is a commodity supplement costing pennies, Calcidiol is a specialized compound.
- Prescription (Rayaldee, Calderol): Often prescribed for Chronic Kidney Disease (CKD) to manage secondary hyperparathyroidism. It is highly effective but strictly regulated in high doses.7 4
- Consumer Supplements (e.g., d.velop): In the US, Calcidiol is available over-the-counter under specific brands (like d.velop). These products use a fermentation-derived form of calcifediol and claim to raise levels 3x faster than standard D3.5
- Cost: Standard Vitamin D3 costs ~\$10–\$15 for a year's supply. Calcidiol supplements can cost \$20–\$50 per month.[^8]7
4. Safety and Recommendation
Because Calcidiol is more potent, "more" is not always better.
- Hypercalcemia Risk: Rapidly elevating Vitamin D levels can lead to excess calcium in the blood (hypercalcemia), which can cause kidney stones or heart issues. While studies show Calcidiol is generally safe, it requires monitoring if taken in high doses.[^9]4
- Testing is Crucial: Before switching to Calcidiol for weight loss, you should test your current 25(OH)D levels. If they are already optimal (>50 ng/mL), additional supplementation of either form is unlikely to aid weight loss.
Conclusion:
Yes, Calcidiol is superior to Vitamin D3 for weight loss in overweight individuals because it bypasses fat sequestration and liver processing issues. However, it is significantly more expensive and should be used with guidance to avoid excessive levels.
Perplexity AI on the Mediterranean hypocaloric diet
A Mediterranean hypocaloric diet is essentially a standard Mediterranean eating pattern modified to create a modest daily calorie deficit for weight loss while preserving its cardiovascular and metabolic benefits. It emphasizes plant-based, minimally processed foods and healthy fats, but with attention to portion sizes and total energy intake.2 3 4 5
Core concept
A “hypocaloric” diet means eating fewer calories than the body expends, usually by reducing daily intake by about 400–700 kcal depending on baseline needs and goals. When applied to a Mediterranean pattern, this restriction is achieved mostly by controlling portions of calorie-dense items (oils, nuts, cheese, sweets, refined grains) rather than cutting entire food groups.3 4 5
Typical macronutrient profile
Clinical protocols commonly use roughly 50–55% of calories from carbohydrates, 15–20% from protein, and about 25–30% from fat, with an emphasis on mono- and polyunsaturated fats, especially olive oil and nuts. Fiber intake is kept relatively high (about 25–30 g/day) via vegetables, fruits, legumes, and whole grains to improve satiety and glycemic control.4 5 6
Foods emphasized and limited
- Emphasized: vegetables, fruits, legumes, whole grains, nuts, seeds, extra‑virgin olive oil, fish and seafood, modest amounts of poultry, eggs, and fermented dairy (e.g., yogurt).5 6 2
- Limited: red and processed meats, refined grains, added sugars, sweets, ultra‑processed snacks, and large amounts of cheese and butter.2 5
- Alcohol: if used, typically small amounts of wine with meals, and may be omitted entirely for metabolic or liver concerns.5
Weight loss and body composition
Trials in people with overweight or obesity show that a hypocaloric Mediterranean diet produces clinically meaningful weight loss (around 5–7% of initial body weight over several months) with preferential reduction in fat mass and relative preservation of fat‑free mass compared with some other hypocaloric patterns. Some studies report early improvements in insulin and leptin within 1–4 months even with modest weight loss, suggesting beneficial metabolic adaptations beyond the scale change.1 4
Metabolic and cardiovascular effects
This approach is associated with improvements in insulin sensitivity, HOMA‑IR, and inflammatory markers in individuals with obesity or metabolic syndrome. Longer‑term Mediterranean-pattern weight‑loss interventions also reduce blood pressure, improve lipid profile, and lower overall cardiovascular risk, especially when combined with regular physical activity.7 1 4 5
Practical structure for implementation
In practice, a Mediterranean hypocaloric plan usually involves:
- Calculating approximate energy needs and reducing daily intake to about 1,200–1,600 kcal for many adults, adjusted for sex, size, and activity.3 4
- Building meals around high‑volume, low‑energy‑density foods (vegetables, salads, broth‑based soups, fruit) to maintain satiety while staying within calorie targets.3
- Using olive oil, nuts, and seeds in measured portions rather than free‑pouring, given their high calorie density (e.g., ~9 kcal/g for oils vs <0.3 kcal/g for many vegetables).3
If you like, a next step could be to sketch a 1–2 week template tailored to your kcal target and specific metabolic goals (e.g., insulin resistance, NAFLD, sarcopenia) while maintaining a Mediterranean hypocaloric framework.