Nopal cactus is a species of cactus that is native to Mexico but can also be found in other parts of Latin America, South Africa, and the Mediterranean. It is a versatile plant that is not only consumed as food but also used in traditional medicine for its medicinal properties. The fruit of the nopal cactus, known as prickly pear which is rich in dietary fiber, vitamin C, calcium, betalain, and polyphenols with antioxidant properties.
Whether or not Nopal Cactus benefits weight loss or not is certainly a matter for debate. Most of the claims around it stem from a very small amount of human studies and a lot of ones in animals. These claims are typically that Nopal Cactus binds to fat, meaning that you don't digest it. This is what is known as a lipase inhibitor. Lipase inhibitors do in fact exist and are available both over the counter and via clinicians in some countries, but that doesn't necessarily mean that Nopal Cactus is one, or that it is potent enough to be particularly effective for humans.
It is also worth mentioning that whilst a lot of supplements claim that Nopal can help weight loss, in the successful human studies a typical dietary intervention may include a personalized diet plan with an energy restriction of 500 kcal per day, along with the addition of 300 g of boiled nopal daily. This was along side healthy diet and excersise. Examples being a 2100kcal diet and 30 mins of brisk walking a day. The diet had to include 375g of nopal.  In this case the group eating the nopal cactus did in fact lose more weight. And with this amount of nopal more fat has been measured in stool samples, showing it does work to bind fat, you just need quite a lot of it. There is also some evidence to suggest that taken in this volume it can effect your gut microbiome and decrease appetite.
This means that said supplements which largely contain 1 gram of nopal cactus. like PhenQ, aren't likely to have nearly the same effect.
Nopal Cactus Weight Loss: The Evidence
Obesity is a global epidemic, and finding effective weight management solutions is a top priority. Nopal cactus has gained attention as a natural aid for weight loss due to its unique properties. The fiber present in nopal acts as a natural blocker of fats and sugars. When ingested, the fiber forms an insoluble complex with dietary fats, preventing their digestion and absorption.  As a result, these fats are eliminated from the body without contributing to calorie intake. This reduction in calorie absorption can lead to weight loss, especially when combined with a balanced diet and regular exercise as is evidences by other lipase inhibitors. 
The Role of Nopal Cactus in Fat Binding
The ability of nopal cactus to bind fats is a key factor in its weight loss potential. The fiber present in nopal forms a complex with dietary fats, creating an insoluble matrix that cannot be digested or absorbed by the body. This complex is then eliminated through fecal excretion, effectively reducing the amount of fat available for absorption. By decreasing the absorption of dietary fats, nopal cactus may help individuals achieve their weight loss goals. Generally speaking however, fat binders are less effective than appetite suppressants in helping with weight loss goals. As a result, there are better natural options to assist with weight loss.
Scientific Evidence and Clinical Studies
Several scientific studies have investigated the effects of nopal cactus on weight loss in both animal and human models. One study conducted on obese Zucker rats  found that a diet supplemented with nopal cactus led to a significant reduction in hepatic triglyceride levels, hepatomegaly, and biomarkers of hepatocyte injury. The rats fed the nopal diet also showed a higher serum concentration of adiponectin, a hormone involved in regulating glucose and fatty acid metabolism.
In a clinical trial involving overweight and obese adults, the consumption of nopal cactus was shown to promote fecal fat excretion, indicating a reduction in the absorption of dietary fats.  This finding supports the notion that nopal cactus can bind to dietary fats and increase their excretion, thereby reducing their availability for absorption.
Another clinical investigation evaluated the effects of nopal consumption on the development of hepatic steatosis (fatty liver) and oxidative stress in obese Zucker rats. The results showed that rats fed a diet containing nopal had significantly lower hepatic triglyceride levels and reduced oxidative stress markers compared to the control group. These findings suggest that nopal consumption can attenuate hepatic steatosis by increasing fatty acid oxidation and improving liver insulin signaling.
Does Norpal Cactus Suppress Appetite
One study conducted on obese women showed that a dietary intervention comprising caloric restriction, physical activity, and nopal supplementation led to significant reductions in body mass index (BMI), weight, waist circumference, and cholesterol levels. These improvements were accompanied by modifications in the gut microbiota composition, including an increase in beneficial bacteria such as Prevotella and Roseburia. This led to the suggestions that the effects of nopal on weight loss and metabolic health are believed to be partly mediated by its impact on the gut microbiota. Nopal consumption can modulate the gut microbiota composition, increasing the abundance of beneficial bacteria involved in fiber degradation and short-chain fatty acid (SCFA) production. SCFAs, such as butyrate, have been shown to exert anti-inflammatory effects, improve insulin sensitivity, and promote satiety. 
Secondary Ways In Which Nopal Cactus Could Benefit Weight Loss
The Link Between Nopal Cactus and Blood Glucose Control
One area where nopal cactus has shown promise is in blood glucose control. Several studies have demonstrated its ability to regulate blood sugar levels in both healthy individuals and those with type 2 diabetes. The high fiber content of nopal, including mucilages, pectins, and hemicelluloses, is believed to be responsible for its beneficial effects on blood glucose and cholesterol levels. By inhibiting the absorption of glucose and cholesterol in the bloodstream, nopal cactus may help manage these metabolic parameters. This makes it a potentially valuable supplement for individuals with diabetes or hypercholesterolemia.
Antioxidant and Anti-Inflammatory Effects of Nopal Cactus
In addition to its effects on weight loss, nopal cactus has been shown to have antioxidant and anti-inflammatory properties. The polyphenols and betalains present in nopal act as powerful antioxidants, scavenging free radicals and reducing oxidative stress in the body. Oxidative stress is known to contribute to various diseases, including obesity. By reducing oxidative stress, nopal cactus may help mitigate the negative effects of obesity on overall health.
Furthermore, nopal cactus has been found to possess anti-inflammatory properties. Chronic low-grade inflammation is a common characteristic of obesity and is associated with insulin resistance and other metabolic abnormalities. Preliminary studies suggest that nopal cactus may help modulate inflammation by influencing the gut microbiota and reducing the production of pro-inflammatory cytokines.  This anti-inflammatory effect could further contribute to the weight loss benefits of nopal cactus as it could help people with sore joints move more.  Particularly in older populations. However, there are far more potent anti inflammatory plants, such as turmeric which contains curcumin or ginger and galangal.
Does Nopal Cactus Help Weight Loss? Conclusion
Nopal cactus, with its abundance of beneficial compounds, shows great promise in the fight against obesity and its associated health risks. While the results from studies on its effects can be conflicting, there is evidence to suggest that nopal cactus extract can suppress fat storage and improve metabolic parameters. But, that is in the case of eating a notable volume of it as part of a healthy diet, not supplementing a small amount of it.
1 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8912383/
2 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5308786/
3 - https://pubmed.ncbi.nlm.nih.gov/32485574/
4 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5498631/
5 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4109417/
8 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8389628/