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Let's be clear from the first line: no "fat burner" makes you lose meaningful fat on its own. The US NIH Office of Dietary Supplements concludes that the evidence for most of these products is weak. What really reduces body fat is energy balance, enough protein, strength training, activity volume, sleep and adherence to the plan. None of that comes in a capsule.
So why this guide? Because if you are going to consider a thermogenic as a complement to a solid base, you deserve to know which ingredients have real evidence, which are marketing, how much caffeine they carry and which risks matter for a runner. We reviewed 8 products available in Spain — with a special focus on label transparency — including the AMIX Burn & Dry, and we ranked them on verifiable criteria, not commission.
Quick answer
If you want the real effect without paying for smoke: the most honest option is usually the simplest — caffeine in an adjustable dose. Among the ingredients in this comparison, it is the one with the most consistent evidence for improving specific aspects of performance; its effect on fat loss is small.
If you want a transparent thermogenic formula: HSN Evoripped and AMIX Burn & Dry declare all their doses, which is rare in this category. Watch out: the AMIX includes a strong diuretic block, which sheds water, not fat.
If you are caffeine-sensitive or train at night: a stimulant-free option (L-carnitine) won't interfere with sleep, though its evidence for fat loss is weak.
Most important: supplements have a secondary effect versus diet, strength, rest and consistency. A fat burner won't fix a badly planned approach, and losing weight aggressively can ruin your training. Start with the base.
- Quick summary (table)
- The 8 fat burners reviewed
- What a fat burner really is
- What they can and can't do
- Ingredients with the best evidence
- Ingredients with weak evidence or marketing
- With caffeine vs stimulant-free
- Risks of combining several products
- How to choose as a runner
- When NOT to use it (RED-S)
- Safety, contraindications and anti-doping
- Nutrition and training to lose fat
- Frequently asked questions
- Editorial methodology
- Sources and verification
Quick summary
We only state caffeine when the manufacturer declares it. "See label" means the product contains stimulants but does not publish the exact amount per dose. We do not include prices: use the button to check the current price and availability.
| # | Product | Type | Stimulants | Caffeine | Format / servings | Highlight |
|---|---|---|---|---|---|---|
| 1 | HSN Evoripped | Thermogenic capsules | Yes (high) | 300 mg/dose | 120 caps | Best transparent thermogenic |
| 2 | AMIX Burn & Dry | Capsules (thermogenic + diuretic) | Yes (high) | 100 mg PurCaf® + 22% guarana; total not consolidated | 90 capsules · 30 servings | Most transparent label |
| 3 | HSN Caffeine Anhydrous 200 mg | Caffeine tablets | Caffeine only | 200 mg/tablet | 120 tabs | Best simple formula |
| 4 | HSN L-Carnitine L-Tartrate 3000 | Capsules | No | No | 120 caps | Best stimulant-free |
| 5 | Weider Fat Burner | Thermogenic capsules | Yes | See label | 120 caps | Established brand |
| 6 | MyProtein CLA 1000 mg | Capsules (CLA) | No | No | 180 caps | CLA (limited evidence) |
| 7 | Life Pro Thermo 10 | Thermogenic capsules | Yes | See label | 90 caps | Spanish brand |
| 8 | Weider Thermo Caps | Thermogenic capsules | Yes | See label | See label | Caffeine + appetite |
The 8 fat burners reviewed
1. HSN Evoripped — Best transparent thermogenic
Highlight: the most honest thermogenic on its label
HSN's Evoripped, a Spanish brand, does what almost none do: it declares its doses. It provides 300 mg of caffeine per serving, green tea EGCG and p-synephrine, in vegan capsules. It carries a high stimulant load, but the transparent label lets you know exactly what you are taking and add it to the rest of your daily caffeine.
Be realistic about what those ingredients deliver: caffeine has solid evidence on performance; green tea and synephrine have small metabolic effects. None "burns fat" by itself.
Pros
- Declares caffeine (300 mg) and the other actives
- Vegan capsules, Spanish brand
- Lets you calculate your total daily caffeine
Cons
- High stimulant load: mind your sleep and blood pressure
- Contains synephrine (cardiovascular caution)
- The effect on fat is small
Verification: product listing on Amazon Spain (120 capsules, 300 mg caffeine, EGCG and p-synephrine, vegan).
2. AMIX Burn & Dry 90 capsules — The most transparent label (thermogenic + diuretic)
Highlight: it details most ingredients on the label
AMIX's Burn & Dry (Black Line) stands out for something we value a lot: it details most of its ingredient amounts on the label. Per 3-capsule dose, the official spec declares 100 mg of PurCaf® caffeine and 100 mg of dry guarana extract standardised to 22% caffeine, plus 20 mg of synephrine (Citrus aurantium), 300 mg of Sinetrol® XPUR, 200 mg of green tea, 5 mg of BioPerine® and a strong diuretic block: 450 mg of horsetail, 300 mg of dandelion and 300 mg of nettle. The brand does not show an unambiguous consolidated caffeine total on this spec, so we cannot claim it is 200 mg per dose: the guarana and Sinetrol® themselves add caffeine that the label does not sum explicitly. The official directions are 3 capsules 30-60 minutes before exercise.
The honest caveat, and it matters: that diuretic block sheds water, not fat. The scale may drop fast, but it is fluid that returns when you rehydrate. For a runner, diuretics around training are counterproductive: you need hydration and electrolytes. We place the AMIX second for its exemplary label transparency, not because it is the most suitable for everyone: it is a specific-profile product (drainage + stimulants) with a considerable caffeine and synephrine load.
Pros
- Details most doses on the label (uncommon transparency)
- Caffeine from two declared sources (PurCaf® + 22% guarana)
- Well-known brand, 90-capsule blister format
Cons
- The diuretic component = water, not fat
- High stimulant load + synephrine (CV caution)
- May contain traces of milk, egg, soy, gluten and shellfish; not for pregnancy, breastfeeding or children
Verification: official Amix Store page (90 capsules, 3 caps/dose, 100 mg PurCaf® caffeine + 100 mg guarana at 22%, synephrine 20 mg, diuretics and warnings). No consolidated caffeine total per dose is stated.
3. HSN Caffeine Anhydrous 200 mg — Best simple formula
Highlight: the ingredient with evidence, no filler
Here is the editor's pick for many runners: caffeine only, 200 mg per tablet, which you can split to adjust the dose. Among the ingredients in this comparison, caffeine is the one with the most consistent evidence for improving specific aspects of performance (endurance gains of around 2-4% at 3-6 mg/kg, per the ISSN position stand). Its effect on fat loss is small. You pay for what works, with no proprietary blends or synephrine.
Pros
- Transparent and cheap per dose
- Fully adjustable dose
- No synephrine or filler
Cons
- It's caffeine: don't expect "fat-burning" effects
- Easy to overdo if you add other sources
- Tolerance with habitual use
Verification: Amazon Spain listing (200 mg caffeine per tablet, 120 units).
Losing fat starts with training well
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4. HSN L-Carnitine L-Tartrate 3000 — Best stimulant-free option
Highlight: no caffeine, no sleep interference
If you don't tolerate stimulants or train in the evening, this HSN L-carnitine L-tartrate provides 3,000 mg daily with no caffeine, in vegan capsules. Let's be honest: the evidence for oral carnitine to lose fat is weak and inconsistent — muscle carnitine is hard to raise with oral dosing. Its value here is different: a clean, stimulant-free option with no sleep risk, for anyone who wants to try without loading up on caffeine.
Pros
- No stimulants, doesn't affect sleep
- Clear label (3,000 mg), vegan
- Generally well tolerated
Cons
- Weak evidence for fat loss
- May cause GI discomfort in some people
Verification: Amazon Spain listing (L-carnitine L-tartrate 3,000 mg/day, 120 capsules, vegan).
5. Weider Fat Burner — Established brand
Highlight: one of the most established brands
Weider is a classic sports-nutrition brand, and its Fat Burner is a thermogenic formula with caffeine and plant extracts in 120 capsules. It's a recognisable option; check the official spec for the exact amounts of each ingredient before adding it to your daily caffeine.
Pros
- Veteran, accessible brand
- Large format (120 capsules)
Cons
- Doesn't always detail mg per ingredient
- Contains caffeine: add it to your day
Verification: Amazon Spain listing (120 capsules, thermogenic formula with caffeine; check amounts on the official spec).
6. MyProtein CLA 1000 mg — CLA (limited evidence)
Highlight: a single, transparent ingredient (though weak evidence)
MyProtein's CLA (conjugated linoleic acid) is a single-ingredient product with a clear label. We include it for transparency, but honestly: the evidence for CLA to reduce fat is weak — meta-analyses show small effects (around −0.4 kg) that disappear when you keep only the high-quality studies. At higher doses there are also concerns about metabolic markers. It is not our recommendation for a runner.
Pros
- Single, transparent ingredient
- No stimulants; recognisable brand
Cons
- Weak evidence for fat loss
- Possible GI discomfort; caution at high doses
Verification: Amazon Spain listing (CLA 1,000 mg, 180 capsules).
7. Life Pro Thermo 10 — Spanish brand
Highlight: a Spanish brand with a multi-ingredient formula
Life Pro is a widely available Spanish brand, and its Thermo 10 is a multi-ingredient thermogenic formula in 90 capsules. As with any complex formula, the key is to check its official spec: the more ingredients a formula has, the more it matters to know the real doses of each and the total stimulant load.
Pros
- Well-known Spanish brand
- Complete formula
Cons
- Many ingredients: check doses and stimulants on the label
- Contains stimulants: assess your total caffeine
Verification: Amazon Spain listing (90 capsules, thermogenic formula; check composition on the official spec).
8. Weider Thermo Caps — Caffeine and appetite control
Highlight: a classic thermogenic with an appetite focus
Weider's Thermo Caps are another thermogenic formula with caffeine, also aimed at the feeling of satiety. Appetite control is a factor that can help maintain the deficit, but the evidence for these products is modest and very context-dependent. Check the official spec for the exact composition.
Pros
- Veteran brand
- Satiety focus
Cons
- Composition to check on the label
- Contains caffeine: add it to your day
Verification: Amazon Spain listing (thermogenic formula with caffeine; check composition and dose on the official spec).
What a fat burner really is
Under the "fat burner" or "thermogenic" label sit very different supplements: some provide caffeine and other stimulants; others add plant extracts, diuretics or supposed "metabolism boosters". The name promises a lot, but the real mechanism is modest: at most, some ingredients slightly raise energy expenditure or fat oxidation, mildly reduce appetite, or improve energy and focus in a session. None "melts" fat.
What they can and can't do
What some can do (modestly, and not for everyone): provide energy and focus before training (caffeine), slightly lower perceived exertion, raise thermogenesis a little and, in some contexts, help with appetite.
What they cannot do: cause meaningful fat loss on their own, burn "spot fat" (fat loss is always global), replace a calorie deficit, or guarantee results. And a key point: many products that make the scale drop fast do it through water loss (diuretics), not fat; that weight returns when you rehydrate.
Ingredients with the best evidence
- Caffeine: the best-supported ingredient, but on performance (~2-4% endurance gains at 3-6 mg/kg), not on fat. Its thermogenic and appetite effect is small and fades with habitual use.
- Green tea extract (EGCG): combined with caffeine, small effects (around −0.4 kg vs a caffeine control); without caffeine, no significant effect. EFSA warns that ≥800 mg/day of EGCG from supplements may be associated with signs of liver injury.
- Capsaicin/capsinoids: raise energy expenditure by around 50-70 kcal/day, mainly in overweight people; the effect on weight is marginal.
Ingredients with weak evidence or overblown marketing
- Synephrine (bitter orange): small effect; the caution is the combination with caffeine (raised blood pressure and heart rate). Bitter-orange formulas are also a frequent vehicle for contamination in this category.
- L-carnitine: weak, inconsistent evidence for fat loss via oral dosing.
- Chromium (picolinate): a Cochrane review estimates −1.1 kg, of "debatable clinical relevance" and low-quality evidence.
- CLA: a small effect that disappears in high-quality studies.
- Garcinia cambogia (HCA): weak-to-null evidence and, importantly, signs of liver injury in published cases. We do not recommend it.
- Choline: "rapid loss" data come from weight-class sports and reflect body mass/water, not fat.
- Black pepper (piperine/BioPerine®): not a burner; it's an absorption enhancer. It can raise the bioavailability of other ingredients... and of medications too (interaction risk).
- Plant diuretics (horsetail, dandelion, nettle): they shed water, not fat; for a runner, they compromise hydration and electrolytes.
- Proprietary blends: they hide the dose of each ingredient. You can't tell if something is under-dosed or if you are stacking too many stimulants, and safety or interactions can't be assessed.
Fat burners with caffeine vs stimulant-free options
Most "burners" are, at heart, caffeine with companions. A formula with caffeine (HSN Evoripped, AMIX Burn & Dry, Weider) can give you energy before training, but it adds to your total daily caffeine and may affect sleep. A stimulant-free option (L-carnitine, CLA) won't interfere with rest, but its evidence for fat loss is weak. There is no universal choice: it depends on your sensitivity, your training schedule and how much caffeine you already have.
Risks of combining several products
How to choose a supplement as a runner
- Prioritise transparency: choose products that declare their doses (avoid proprietary blends).
- Count your total daily caffeine including coffee, gels and pre-workouts.
- Think about sleep: if you train in the evening, avoid stimulants or pick a caffeine-free option.
- Be wary of diuretics: losing water is not losing fat, and it costs you hydration.
- Test tolerance in training, never on race day.
- If you're tested: look for independent batch certification (e.g. Informed Sport), knowing it reduces but does not eliminate the risk.
- Don't exceed the manufacturer's dose and stop at any adverse symptom.
When NOT to use it: energy availability and RED-S
This is where fat burners can do real harm: when used to compensate for eating little and training a lot. When the energy left after training is insufficient over time (low energy availability), you can slip into RED-S (Relative Energy Deficiency in Sport). The IOC consensus describes consequences for metabolism, hormonal and menstrual function, bone health, immunity, protein synthesis and mental health, with more stress fractures and more illness. Endurance sports are among the most exposed.
A runner should not use stimulants to paper over lack of sleep, an excessive deficit, poor recovery, training overload or insufficient nutrition. If that sounds like you, a fat burner won't fix it. We are not diagnosing: if warning signs appear (persistent fatigue, repeated injuries, menstrual changes), consult a sports physician or a dietitian.
Safety, contraindications and anti-doping
These supplements may not be suitable for: minors; pregnancy or breastfeeding; caffeine-sensitive people; those with cardiovascular problems or hypertension; anxiety or significant sleep disorders; anyone on medication; and athletes with relevant medical history. No supplement is "100% safe". When in doubt, consult a doctor or dietitian.
Nutrition and training to lose fat without hurting performance
The strategy that works doesn't fit in a capsule:
- A moderate, sustainable deficit, not aggressive, to protect recovery and performance.
- Enough protein to preserve muscle in a deficit. See our protein guide for runners.
- Strength training 2-3 days a week, on top of running.
- Daily activity volume (NEAT): move more throughout the day.
- Sleep and load management: poor sleep sabotages appetite and fat loss.
- Adherence: the best plan is the one you can keep. A structured training plan helps you sustain it.
Frequently asked questions
Do fat burners actually work?
Not the way marketing sells them. None causes meaningful fat loss on its own; the NIH Office of Dietary Supplements considers the evidence for most weak. What drives fat loss is energy balance, protein, strength, activity volume, sleep and adherence. Some ingredients, especially caffeine, have a modest effect on energy or performance, not on fat.
What is the best fat burner for running?
For a runner, the most honest option is usually the simplest: caffeine in an adjustable dose. Among the ingredients in this comparison, it is the one with the most consistent evidence for improving specific aspects of performance; its effect on fat loss is small. If you prefer a thermogenic formula, HSN Evoripped and AMIX Burn & Dry declare most of their doses. The stimulant load and the effect on sleep matter more than the ingredient list.
Can you take it before training?
Many are taken 30-60 minutes before for their caffeine. The problem is the total with coffee, pre-workouts and gels: it's easy to exceed reference amounts (EFSA: ~400 mg/day, ~200 mg per dose). Test tolerance in training, never on race day.
Can I combine it with coffee or caffeinated gels?
Yes, but add up all your caffeine for the day. Many burners hide 150-300 mg per dose, plus synephrine or other stimulants. Overdoing it worsens sleep, and poor sleep sabotages exactly what drives fat loss.
Does it help lose belly fat?
There is no spot reduction. No supplement burns fat from a specific area; fat is lost globally with a sustained deficit, and where you lose it first depends on genetics.
Can it affect sleep?
Yes, through caffeine. EFSA notes that 100 mg near bedtime can increase how long it takes to fall asleep. Since sleep is key for recovery and appetite regulation, a burner that costs you sleep is counterproductive.
Is a formula with or without caffeine better?
It depends on you. Caffeine is the best-supported ingredient, but if you are sensitive, train at night or already have a lot, a stimulant-free option avoids interfering with sleep, though its evidence for fat loss is weak.
Are they suitable during race preparation?
Only with great caution. Aggressive weight loss during a block reduces energy availability and raises the risk of fatigue, injury and poor performance (RED-S). Don't use stimulants to compensate for lack of sleep or an excessive deficit. Never try a new supplement on race day.
Can a fat burner cause an anti-doping positive?
It's a real risk. Even when ingredients are legal, supplements can be contaminated with prohibited substances not listed on the label; anti-doping bodies warn about this risk repeatedly. Higenamine is prohibited by WADA and pharmaceutical diuretics too. A label saying "no prohibited substances" is not a guarantee. Look for independent batch certification.
How long can you use it?
There is no universal medical duration. Follow the label and don't exceed the manufacturer's dose. Tolerance develops to some of caffeine's effects, but there is no universal cycling protocol; many users take periodic breaks. Stop at any adverse symptom and consult a healthcare professional.
Editorial methodology
To assess and rank these 8 products we applied, in this order: label transparency; declared ingredients and amounts; suitability for runners and hybrid athletes; total stimulant load; ease of adjusting the dose; risk of sleep interference; compatibility with training; number of doses; quality of the official spec; the relationship between formulation and cost (without publishing prices); warnings; and possible anti-doping risk. This is not a blind scientific trial but an editorial comparison. We have not personally tested these products nor received any for free for this guide; the information comes from the official specs and the cited scientific evidence.
Sources and verification
- NIH Office of Dietary Supplements — Dietary Supplements for Weight Loss: consumer fact sheet (weak evidence for most products).
- USADA — Caffeine profile (not prohibited; Monitoring Program; ~400 mg/day).
- EFSA — Safety of green tea catechins (liver signal at ≥800 mg/day EGCG from supplements).
- Cochrane — Chromium picolinate (−1.1 kg, debatable clinical relevance).
- Stohs et al., p-synephrine/Citrus aurantium review: PMC5655712 (caution with the caffeine combination).
- USADA — Higenamine (WADA-prohibited substance found in fat burners).
- IOC 2023 — consensus on RED-S and low energy availability: consensus summary.
- WADA — current Prohibited List (diuretics and masking agents).
- Official product specs: AMIX Burn & Dry (Amix Store) and the product listings on Amazon Spain.
