Does Ashwagandha Make You Fat or Cause Weight Gain?

Ashwagandha does not cause fat gain. Across multiple clinical trials, the supplement has either had no meaningful effect on body weight or has modestly reduced it, particularly in people dealing with chronic stress. The concern likely stems from temporary bloating, water retention, or the number on the scale creeping up as muscle mass increases. But the biological pathways ashwagandha influences, from cortisol to testosterone to food cravings, mostly push in the opposite direction of gaining fat.

What Clinical Trials Show About Ashwagandha and Body Weight

Two randomized, placebo-controlled trials have directly measured body weight changes in adults taking ashwagandha. In one trial of chronically stressed adults, ashwagandha root extract led to improvements in body weight and body mass index compared to placebo, with the researchers concluding it could be useful for weight management in that population.¹ A more recent trial reported even more dramatic results: the ashwagandha group lost roughly 8.5 kg on average, compared to about 2.4 kg in the placebo group, with a corresponding drop in BMI.² Both studies focused on people under chronic stress, which is an important detail. Stress-related weight gain and general overeating follow different patterns, and ashwagandha’s effects seem most relevant when stress hormones are part of the picture.

These are small trials with specific populations, so the results should not be taken as proof that ashwagandha is a weight-loss supplement for everyone. But they do make it hard to argue that ashwagandha causes weight gain. In every controlled study where body weight was tracked, the ashwagandha group either lost more weight than placebo or stayed the same.

How Cortisol Reduction Ties Into Weight

The most well-studied mechanism behind ashwagandha’s effects on stress is its influence on the body’s stress-response system. In stressed adults, ashwagandha appears to moderate the activity of the hormonal cascade that produces cortisol, reducing morning cortisol and the stress hormone DHEA-S.³ A meta-analysis pooling data from multiple trials found a statistically significant reduction in serum cortisol levels with ashwagandha compared to placebo.⁴ A separate meta-analysis confirmed this, finding cortisol dropped by about 1.16 µg/dL on average.⁵

This matters for weight because chronically elevated cortisol is one of the clearest hormonal drivers of fat storage, especially around the midsection. High cortisol encourages the body to hold onto visceral fat, ramps up appetite, and increases cravings for calorie-dense foods. By dialing down cortisol, ashwagandha may remove one of the hormonal signals that pushes the body toward fat accumulation. This is also the most logical explanation for why the weight-loss effect is most pronounced in chronically stressed people: they have the most cortisol to bring down.

Ashwagandha and Food Cravings

Beyond the hormonal route, there is evidence that ashwagandha directly reduces the urge to overeat. A double-blind trial in college students found that those taking ashwagandha experienced significantly lower food cravings over time compared to the placebo group.⁶ The effect appeared within about 30 days. Reduced cravings mean fewer impulsive snacking episodes, which is one of the ways chronic stress leads to gradual weight gain. If you are someone who reaches for comfort food when anxious or overwhelmed, this pathway alone could mean ashwagandha tips the scale in favor of weight loss rather than gain.

It is worth noting that the craving reduction seen in the study was tied to stress management, not appetite suppression in the traditional sense. Ashwagandha is not a stimulant and does not seem to blunt hunger signals the way caffeine or certain pharmaceuticals do. The mechanism appears to be about calming the stress-driven override that makes people eat when they are not actually hungry.

Body Composition Shifts That Can Confuse the Scale

Here is where things get interesting and where some of the “ashwagandha made me gain weight” anecdotes probably originate. When people combine ashwagandha with resistance training, studies consistently show improvements in body composition. One trial found that subjects taking ashwagandha had a significantly greater decrease in body fat percentage (about 3.5% versus 1.5% for placebo) and a significantly greater increase in testosterone.⁷ A recent meta-analysis of resistance-training studies confirmed the strength gains: ashwagandha users showed greater improvement in upper-body and lower-body strength and chest circumference compared to placebo.⁸

Muscle is denser than fat. If you are losing fat and gaining muscle simultaneously, your body looks leaner and your clothes fit differently, but the number on the scale might not budge or might even tick upward. Someone who starts taking ashwagandha alongside a gym routine and sees the scale go up by a couple of pounds is not gaining fat. They are gaining lean tissue while possibly losing fat at the same time. This is a positive shift in body composition, but if you are only watching the scale, it can feel alarming.

The meta-analysis did find that the pooled effect on body fat percentage across studies was not statistically significant, which is a useful reality check. The strength and muscle-size benefits are more reliable than the fat-loss effect when ashwagandha is used as a workout supplement.⁸ In other words, ashwagandha consistently helps you build muscle, but whether it independently strips away fat during exercise is less certain.

Bloating, Water Retention, and the “Puffy” Phase

A common complaint among people who start taking ashwagandha is a temporary feeling of puffiness or bloating, especially in the first few weeks. This is not the same thing as gaining body fat, though it can easily be mistaken for it on the scale or in the mirror. The NIH notes that stomach upset, loose stools, nausea, and drowsiness are the most common mild side effects reported in clinical trials, with most people tolerating the supplement well for up to about three months.⁹ Digestive changes during the adjustment period can lead to temporary water retention and abdominal bloating that resolves as the body adapts.

If you notice your face or belly looks slightly swollen in the first couple of weeks on ashwagandha, that is likely water, not fat. Staying well hydrated and giving your body two to four weeks to adjust is usually enough. If the bloating persists beyond a month or is uncomfortable, it may be worth trying a different form of the supplement (capsule versus powder, for instance) or taking it with food.

Testosterone, DHEA, and Hormonal Effects on Weight

Ashwagandha’s hormonal effects go beyond cortisol. A crossover study in overweight men found that ashwagandha supplementation raised DHEA-S levels by about 18% and testosterone by about 15% compared to placebo.¹⁰ Higher testosterone generally supports leaner body composition by promoting muscle protein synthesis and making the body more efficient at using fat for energy. For men with low or borderline testosterone, which is common in middle-aged and older adults, this hormonal shift could be especially meaningful.

For women, the hormonal picture is less studied. Most ashwagandha-and-testosterone research has been conducted in men. Women produce testosterone too, just in much smaller quantities, and the effects of modestly raising it are different. It is not clear from the available evidence whether women experience the same body-composition benefits from ashwagandha’s testosterone effects, though the cortisol and stress-related pathways should apply regardless of sex.

The Thyroid Angle

One plausible mechanism by which ashwagandha could theoretically cause weight changes in either direction involves the thyroid. Ashwagandha has been shown in case reports and small studies to stimulate thyroid hormone production. In one case, a 73-year-old woman who had been using ashwagandha extract for two years to self-treat her hypothyroidism developed thyrotoxicosis, essentially an overactive thyroid, with symptoms including a rapid heart rate. Her thyroid levels normalized after she stopped the supplement.¹¹ A review of reported cases found at least three instances of thyrotoxicosis linked to ashwagandha, occurring in both people with preexisting thyroid conditions and previously healthy individuals.¹²

An overactive thyroid speeds up metabolism, which usually leads to weight loss rather than gain. An underactive thyroid, on the other hand, slows metabolism and can cause weight gain. For someone with borderline hypothyroidism, ashwagandha’s thyroid-stimulating effect might slightly boost metabolism and prevent the sluggish weight gain that goes with an underperforming thyroid. But for someone with normal thyroid function, pushing thyroid hormones higher than they should be is not desirable and can cause its own problems, including muscle wasting and heart rhythm issues.

If you have a thyroid condition, are taking thyroid medication, or have a family history of thyroid disease, this is worth discussing with a doctor before starting ashwagandha. The thyroid interaction is probably the single most medically significant consideration around ashwagandha and body weight.

What Animal Studies Suggest About Fat Metabolism

Some of the more exciting findings about ashwagandha and fat come from laboratory studies in mice, which are worth knowing about but should be taken with a large grain of salt. In one study, mice fed a high-fat diet and given ashwagandha extract showed increased energy expenditure driven by improved mitochondrial activity in both brown fat and skeletal muscle. The extract also promoted the conversion of white fat into metabolically active beige fat, a process called “browning” that burns more calories.¹³ The researchers identified withaferin A, a major compound in ashwagandha, as a key driver of this effect.

Separately, a review of the mechanistic literature found that ashwagandha may improve insulin sensitivity and influence glucose metabolism through several enzyme pathways, potentially benefiting people with metabolic syndrome.¹⁴ Better insulin sensitivity means your body handles blood sugar more efficiently, which can reduce the tendency to store excess energy as fat.

These are promising leads, but translating mouse metabolism data to humans is always uncertain. Doses, metabolic rates, and fat biology differ substantially between species. Still, nothing in the animal research suggests ashwagandha promotes fat storage. Every metabolic mechanism studied so far points toward increased energy expenditure and improved fat handling, not the opposite.

When the Scale Goes Up Anyway

Even with all this evidence stacking against ashwagandha-induced weight gain, some people genuinely do notice the number on the scale rising after starting the supplement. Beyond body composition shifts and water retention, there are a few practical explanations worth considering.

First, better sleep. Ashwagandha frequently improves sleep quality, and deeper sleep increases growth hormone release, which can accelerate both muscle repair and the kind of productive hunger that supports lean mass gain. If you are sleeping better and feeling more energetic, you may also be eating more without realizing it, simply because your body is recovering from a sleep-deprived state where appetite was suppressed.

Second, reduced anxiety around food. Some people who are chronically anxious actually undereat. If ashwagandha calms that anxiety, appetite may normalize, which can look like weight gain relative to a previously suppressed baseline. This is the body moving toward a healthier equilibrium, not a pathological response.

Third, individual variability. Not everyone responds the same way to any supplement. If you happen to be someone whose thyroid is slightly stimulated by ashwagandha but whose appetite increase outpaces the metabolic boost, the net result could be a small weight increase. Individual hormone profiles, baseline stress levels, diet, and exercise habits all influence the outcome.

What Happens When You Stop Taking It

A case report documented a patient who experienced tachycardia, insomnia, and anxiety after abruptly stopping ashwagandha at 600 mg per day, suggesting that sudden cessation can cause rebound effects in some people.¹⁵ While this case did not specifically address weight changes, a return of elevated cortisol and stress-driven eating after stopping the supplement could theoretically reverse some of the weight-management benefits seen during use. If you decide to discontinue ashwagandha after taking it for a while, tapering the dose over a week or two rather than stopping cold may help your body readjust more smoothly.

Ashwagandha’s Traditional Reputation as a “Nourishing” Herb

In Ayurvedic medicine, ashwagandha has been classified for centuries as a rejuvenating tonic. Ancient texts describe it as strength-building, nourishing, and capable of enhancing physical vigor.¹⁶ The word “nourishing” in this traditional context does not mean fattening. It refers to building vitality and robust health in people who are depleted, underweight, or recovering from illness. In Ayurveda, ashwagandha was given to people who needed to gain healthy weight and strength, much like a calorie-surplus diet combined with physical work. For someone already at a healthy weight, the same herb would support maintenance and recovery rather than adding bulk.

This dual reputation is actually consistent with what modern research shows. Ashwagandha seems to nudge the body toward homeostasis: reducing cortisol when it is too high, supporting muscle gain when combined with training, and improving metabolic efficiency. It is an adaptogen in the truest sense, helping the body adjust rather than pushing it in one fixed direction. That is also why you will find people online reporting both weight loss and weight gain on ashwagandha. The same supplement can produce different outcomes depending on where someone’s body is starting from.