Can Benfotiamine Cause Weight Gain? Separating Fact from Myth

October 31, 2025 •

4 min read

According to one clinical study on combination supplements, approximately 8% of individuals experienced some weight gain, which raises the question: can benfotiamine cause weight gain? The link between this fat-soluble Vitamin B1 derivative and weight fluctuations is complex, involving metabolic pathways and individual health status, rather than a direct, universal cause-and-effect relationship.

Quick Summary

The relationship between benfotiamine and weight gain is not straightforward, with both human and animal studies yielding mixed results. While some anecdotal reports and studies on combination supplements suggest a potential for weight increase, other research points to anti-obesity effects or a resolution of appetite loss caused by deficiency. Factors like metabolic health and dosage influence the outcome.

Key Points

Not a Direct Cause: Benfotiamine does not directly cause weight gain in healthy individuals and is generally considered safe.
Restores Appetite: For individuals with a vitamin B1 deficiency, benfotiamine can restore normal appetite, leading to healthy weight gain that may be misinterpreted as a side effect.
Metabolic Impact: The supplement improves glucose metabolism by increasing transketolase activity, which may promote a more balanced and efficient metabolism.
Conflicting Evidence: Animal studies have shown anti-obesity effects from benfotiamine, while isolated reports of weight gain typically involve multi-ingredient supplements or other underlying health issues.
Individual Factors Matter: The overall effect on weight depends on your existing metabolic health, diet, activity level, and the presence of any underlying health conditions.
Consult a Doctor: It is always best to speak with a healthcare provider, especially if you have pre-existing metabolic conditions, to understand how a supplement might affect you.

Understanding Benfotiamine and Its Role in Metabolism

Benfotiamine is a lipid-soluble derivative of thiamine, or vitamin B1, offering higher bioavailability compared to the water-soluble form. Thiamine is a vital nutrient for carbohydrate metabolism, converting glucose from food into usable energy for the nervous system and muscles. This crucial role in energy production is central to understanding its potential, albeit indirect, impact on body weight.

The Link Between Thiamine Deficiency and Weight

To grasp how benfotiamine influences weight, it's essential to understand the effects of thiamine deficiency. Severe thiamine deficiency is known as beriberi, which has symptoms including lack of appetite, fatigue, and pain in the limbs. In these cases, correcting the deficiency with supplements like benfotiamine can restore normal appetite and improve metabolic function. For individuals who experienced significant weight loss due to deficiency, this restoration can lead to a healthy re-gaining of weight, which is a sign of improved health, not an adverse side effect.

Conflicting Research: Benfotiamine's Role in Weight Regulation

Scientific studies present a mixed picture regarding benfotiamine and weight changes, which explains the confusion surrounding the topic. Some data suggest no link, while other research points to potential anti-obesity effects, especially in specific metabolic contexts.

Studies suggesting no direct weight impact:

One FAQ on the website 1mg.com states directly that benfotiamine does not cause weight gain, linking vitamin B12 deficiency (not B1) to weight loss.
A review of benfotiamine's potential for diabetic complications mentioned that short-term studies found no significant impact on body weight in diabetic rat models.

Studies suggesting anti-obesity effects:

A 2025 study on obese mice found that high-dose thiamine supplementation (the form benfotiamine becomes in the body) significantly inhibited body weight gain and reduced fat tissue accumulation.
Older animal studies on diabetic rats also indicated that benfotiamine significantly decreased body weight gain and reduced adipose tissue weight compared to control groups.
One supplement information site suggests that benfotiamine helps the body use carbohydrates for energy, which could result in weight loss for overweight individuals.

Studies noting weight gain as a possible side effect:

A 2023 article discussing benfotiamine for thyroid patients lists weight gain as a potential short-term adverse effect, though provides no specific context.
In a single clinical study involving a combination supplement of benfotiamine, pyridoxine, and cyanocobalamin, approximately 8% of participants reported weight gain. It is important to note this was not a benfotiamine-only study, and the combination could be responsible for the side effect.

How Benfotiamine Affects Glucose and Metabolism

Benfotiamine's primary benefit for metabolic health is its ability to increase the activity of the transketolase enzyme, a critical part of glucose metabolism. In conditions like diabetes, where blood sugar is high, benfotiamine helps reroute the toxic byproducts of glucose metabolism away from pathways that cause tissue damage. By normalizing metabolic processes, particularly glucose utilization, benfotiamine can help restore metabolic balance. For a person with metabolic issues related to thiamine deficiency, this normalization could lead to a healthier, more balanced weight, which might include gaining weight if they were previously underweight or losing weight if their metabolism becomes more efficient.

Individual Health Factors and Potential for Weight Fluctuation

Numerous factors outside of benfotiamine supplementation can influence weight, making it challenging to isolate the supplement's specific effect. A healthy diet and regular exercise remain the most significant determinants of weight management. In individuals with pre-existing metabolic disorders, such as diabetes or thyroid issues, the supplement's interaction with their condition can produce unique outcomes. The conflicting data from studies, which vary in subject population and dosage, reinforces the need for personalized medical advice.

Comparison of Thiamine Forms and Weight Effects


Feature	Benfotiamine (Lipid-Soluble)	Thiamine (Water-Soluble)
Absorption Rate	Higher bioavailability; absorbed more efficiently by the body	Lower absorption rate; limited by thiamine transporters
Effect on Weight (Deficiency)	Can help reverse weight loss and restore appetite in deficient individuals	Resolving deficiency can lead to weight gain if appetite was previously suppressed
Effect on Weight (Normal Levels)	Research is conflicting; some animal studies show anti-obesity effects, while human studies show potential for gain, especially in combination supplements.	Unlikely to cause weight gain in individuals with adequate vitamin B1 levels.
Metabolic Action	Activates transketolase, redirecting harmful glucose metabolites.	Coenzyme for glucose metabolism, but less effective at higher tissue concentrations.
Target Conditions	Often used for diabetic neuropathy due to its ability to combat advanced glycation end-products (AGEs).	Used for broader thiamine deficiency and beriberi.

Conclusion: The Final Verdict on Benfotiamine and Weight Gain

The idea that benfotiamine universally causes weight gain is largely a misconception, stemming from a misinterpretation of its role in metabolism and the effects of correcting a vitamin deficiency. In individuals with a pre-existing thiamine deficiency, supplementation can restore a normal appetite and metabolism, which can lead to healthy weight gain. Furthermore, some studies, particularly recent animal research, suggest that high-dose thiamine (the metabolite of benfotiamine) may actually have anti-obesity effects by improving glucose and lipid metabolism. Any reported instances of weight gain in clinical studies are often associated with multi-ingredient supplements, making it impossible to single out benfotiamine as the cause. For most healthy individuals taking benfotiamine, significant weight gain is not a common or direct side effect. However, those with underlying metabolic conditions should consult a healthcare professional to understand the complex interplay between their supplement regimen and their specific health needs.

Frequently Asked Questions

No, weight gain is not considered a common or direct side effect of benfotiamine. When it occurs, it is often related to other factors, such as correcting an underlying vitamin B1 deficiency that had caused a loss of appetite and weight loss.

Some limited research, including animal studies, suggests potential anti-obesity effects, as benfotiamine can improve glucose metabolism. By helping the body use carbohydrates more efficiently for energy, it may indirectly support weight management, but it is not a primary weight loss supplement.

In cases of thiamine (vitamin B1) deficiency, which can suppress appetite, supplementation with benfotiamine may help restore normal appetite. For those without a deficiency, there is no strong evidence to suggest it significantly increases appetite.

A study that found weight gain in some participants used a combination supplement containing benfotiamine along with other vitamins, such as pyridoxine and cyanocobalamin. The weight gain may not be solely due to benfotiamine, but could be an effect of the overall formulation or other components.

No. When benfotiamine helps to normalize and improve metabolic function, particularly in individuals with a deficiency or metabolic issues, it can lead to a healthier body weight, which might mean gaining back lost weight or supporting the body's energy use. This is a sign of improved health, not a negative side effect.

Benfotiamine is generally considered safe and well-tolerated, even at higher doses. For long-term weight management, a balanced diet and exercise are the most critical factors. Benfotiamine is more relevant for addressing specific metabolic conditions rather than being a primary weight control tool.

Benfotiamine can improve glucose metabolism, which helps manage blood sugar levels. Better blood sugar control and efficient energy use are beneficial for overall metabolic health and can support a stable body weight, rather than causing weight gain.