“Fat burning creams do NOT burn fat. Period." / "Spot reduction is physically impossible.”

On products applied to the skin: the FTC's position is explicit. Weight loss is an internal metabolic process, nothing worn on or applied to the skin can cause substantial weight loss, and so weight loss claims for patches, creams, lotions, wraps, body belts, earrings and similar products are false. The FTC's Gut Check guidance identifies seven false claims for supplements, herbal remedies, over-the-counter drugs, patches, creams, wraps and similar products, including that a product causes weight loss of two pounds or more a week for a month or more without dieting or exercise, causes substantial weight loss no matter what or how much the consumer eats, causes permanent weight loss after stopping the product, blocks absorption of fat or calories, safely enables loss of more than three pounds a week for more than four weeks, causes substantial weight loss for all users, or causes substantial weight loss by wearing a product on the body or rubbing it into the skin. The FTC has also stated that these "gut check" claims are always false when made for dietary supplements, over-the-counter drugs, or patches, creams, wraps and similar products worn on the body or rubbed into the skin . On spot reduction through exercise: a peer-reviewed meta-analysis pooled 13 studies with 1,158 participants and found no significant effect (confidence interval spanning -0.10 to 0.05, p = 0.508) . The authors describe spot reduction as the belief that specific exercises reduce localized fat depots, where exercising a limb would produce greater fat reduction in adjacent tissue than in the opposite limb, a long-held popular belief , and they framed the review as an attempt to clarify the controversial belief in exercise-induced localized fat reduction . On topical creams and localized fat: here the literature is more complicated than the post allows. A 2023 systematic review in Frontiers in Endocrinology examined topical aminophylline and concluded that the aminophylline topical formulation offers a safe, effective and much less invasive alternative to cosmetic surgery for localized fat reduction , based on trials reporting reduction in thigh or waist circumference from topical aminophylline products, retrieved from PubMed, Web of Science and Scopus through August 2022 . In the original thigh work, subjects who completed the aminophylline trial all lost weight and lost 1.5 plus or minus 0.77 cm more girth on the treated thigh than on the control thigh (p < 0.02), with no rashes or other adverse events . A later trial tested the same approach on the abdomen: the objective was to test whether aminophylline cream applied to the waist reduces waist circumference compared with a control, noting that topical fat reduction from the thigh in women had been demonstrated but not in other body areas or in men , in fifty men and women aged 21 to 65 . In that protocol, participants were placed on a 1,200 kcal/day diet with low impact exercise, and 25 used the aminophylline formula on the waist twice daily for three months , and the formula being tested was developed by one of the authors . On caffeine creams: trials measure cosmetic endpoints rather than fat loss. A double-blind randomized trial of a caffeine nano-cream reported cellulite scores falling from 3.96 to 2.50 in the active group compared with 3.88 to 2.83 with placebo , in a formulation designed to increase caffeine's potential as a skin cosmeceutical, targeting minimisation of cellulite appearance, with sustained delivery of caffeine into and through the skin over 8 hours . Another trial reported that an emulsion with caffeine caused a 17% reduction in the diameter of fatty cells compared with control , and noted that caffeine and its derivatives are used in anti-cellulite cosmetics due to lipolytic activity on fat cells . On capsaicin creams: the supporting evidence is in animals. Topical application of 0.075% capsaicin to male mice fed a high-fat diet significantly reduced weight gain and visceral fat, with markedly smaller fat cells in mesenteric and epididymal adipose tissue , and a review notes that topical 0.075% capsaicin cream applied to mice on a high-fat diet significantly reduced weight gain and visceral fat and also reduced serum glucose and triglycerides . No human trial showing meaningful fat loss from topical capsaicin was located. On sweat belts and sauna suits: no primary human trial was retrieved. Available sources are commercial or consumer-health blogs stating that weight loss from sauna suits is mainly fluid loss rather than fat loss, and sweating alone does not specifically target belly fat , and that the drop on the scale is loss of body fluids, and once you rehydrate after exercise the weight comes right back , with prolonged use risking dehydration and heat exhaustion .