Weight-Loss Supplements,
Honestly Rated

Studied for stress, sold for fat loss

Ashwagandha is an adaptogenic herb with a genuine research base — on perceived stress, anxiety scores and sleep quality. The weight-loss pitch is downstream of that: stress raises cortisol, cortisol is associated with appetite and abdominal fat, therefore lowering stress should reduce fat.

Each link in that chain is weaker than the last. The trials that report weight change tend to be small, short and often conducted in people specifically selected for chronic stress, which limits how far the results generalise. The effect sizes are modest and the primary outcome is usually a stress measure, with body weight as a secondary observation.

They help you absorb more, not less

This is the most clearly mistaken item on the list, and it is worth being precise about why.

Digestive enzymes break food down into molecules small enough to cross your intestinal wall. That is their entire function. Supplementing them, if it does anything in a person with normal digestion, makes absorption more complete — which is the opposite of what someone buying them for weight loss is hoping for.

Enzyme replacement is a real and important therapy for people who cannot make enough of their own, such as in exocrine pancreatic insufficiency or cystic fibrosis. In that context it is prescribed medicine that treats malabsorption. Malabsorption is the condition being corrected, not the goal.

Real biology, marketing well ahead of it

NAD+ is a coenzyme involved in cellular energy metabolism, and it genuinely declines with age. That is real biology, and it is why precursors such as NR and NMN attract serious research interest for ageing and metabolic health.

The gap is between that interest and a weight-loss claim. Much of the striking work is in animal models, and the human trials that exist have generally been small, short, and focused on whether the supplements raise NAD+ levels — which they can — rather than on whether raising those levels causes fat loss. Those are different questions, and the second one does not have an answer yet.

The most oversold item on the list

ACV has been studied for effects on post-meal blood glucose and, in a handful of small trials, on body weight. Some of those trials report modest reductions. They are typically small, short, and run alongside dietary changes that could account for the result on their own.

Even taking the friendliest reading, the effects are far below what the marketing implies, and nothing about vinegar creates a calorie deficit. It is also worth noting that acidic drinks taken regularly can erode tooth enamel and irritate the throat, so the downside is not strictly zero.

The one where the risk deserves attention

Green tea extract is among the better-studied fat-burner ingredients, and the honest reading is that any effect on body weight is small and inconsistent across trials. The caffeine content explains part of what people notice.

What sets it apart is that concentrated extracts have been associated with cases of liver injury, which is why some regulators have issued warnings about high-dose products. This is a rare outcome, but it is a genuine one, and it is a poor trade against an effect size this small. Drinking green tea is a different proposition from taking a concentrated extract.