Not with a stimulant pre-workout: together they stack far past a sensible day of caffeine. Converted to plain caffeine (caffeine citrate is half caffeine by weight, dicaffeine malate about three quarters), one serving of Ninja Burn carries about 360 mg, close to the FDA’s 400 mg a day for most adults on its own, and a high-stim scoop like Ninja Up adds about 400 mg more. Pair a fat burner with a stim-free pre-workout, or pick one.
People ask how to fit fat burners and thermogenics safely into a training routine, and much of Google’s page one is supplement sellers. Here is the arithmetic done properly, and the stack that works.
The Short Version
- The daily line: the FDA cites 400 mg of caffeine a day for most adults, and estimates toxic effects such as seizures with rapid intake of around 1,200 mg (FDA).
- The stack: Ninja Burn plus a high-stim pre-workout comes to about 760 mg of caffeine, about 9.5 mg/kg for an 80 kg lifter; the ISSN links doses around 9 mg/kg to a high incidence of side effects (ISSN position stand, 2021).
- Stimulants add up in your heart rate too: in 12 men doing squats, heart rate ran highest when 100 mg of caffeine joined 100 mg of synephrine (Journal of the American College of Nutrition, 2016).
- Ninja Burn‘s label lists 200 mg caffeine anhydrous, 150 mg dicaffeine malate and 100 mg caffeine citrate per serving; Ninja Swole’s label lists no caffeine at all.
How Much Caffeine Is in a Fat Burner Plus Pre-Workout?
About 760 mg when the pre-workout is a high-stim one. Here is the ledger, line by line, from the two labels.
| Label line | On the label | Plain caffeine | How we worked it out |
|---|---|---|---|
| Ninja Burn: Caffeine Anhydrous | 200 mg | 200 mg | Anhydrous caffeine is caffeine with the water removed |
| Ninja Burn: Caffeine Citrate | 100 mg | 50 mg | Half caffeine by weight (DailyMed drug label) |
| Ninja Burn: Infinergy (Dicaffeine Malate) | 150 mg | About 111 mg | Two caffeine molecules (194.19 each) per malic acid (134.09): 74% caffeine by weight (PubChem) |
| Ninja Burn, one serving | 4 capsules | About 360 mg | 200 + 50 + 111 |
| Ninja Up: Caffeine Anhydrous 300 mg plus Infinergy 135 mg | 1 scoop | About 400 mg | 300 + 100; Ninja Up’s front label says 400 mg deliverable caffeine |
| Burn plus Up, same day | Both | About 760 mg | Nearly double the FDA’s 400 mg |
| Burn plus Ninja Swole | Both | About 360 mg | Swole’s label lists no caffeine |
The dicaffeine malate share is our arithmetic from its name and the molecular weights, not a number printed on the label. Not counted, because the label gives no caffeine figure for them: 200 mg of Dynamine (methylliberine), a caffeine-like compound; 40 mg of synephrine; and the cocoa and green tea extracts. So read about 360 mg as the floor of Burn’s stimulant load, not the ceiling. For context on the methylliberine, a 2020 trial of 125 young adults found 100 to 150 mg a day for four weeks caused no clinically significant changes in heart or blood markers (funded by the ingredient’s distributor); Burn carries 200 mg.
What Happens If You Stack a Fat Burner With a Stimulant Pre-Workout?
You double the stimulant hit, and the FDA’s signs of too much caffeine become the likely outcome: a faster heart rate, palpitations, higher blood pressure, jitters, an upset stomach, nausea, headache and a wrecked night.
The ISSN’s 2021 caffeine position stand found performance gains at 3 to 6 mg/kg, and says very high doses around 9 mg/kg bring a high incidence of side effects without being needed. Burn plus Ninja Up is about 9.5 mg/kg for an 80 kg lifter. That is not more performance; it is more side effects.
Stimulants also stack beyond caffeine. In the 2016 trial, 100 mg of synephrine alone did not change heart rate during squats, but adding 100 mg of caffeine pushed it highest. Ninja Up carries 60 mg of bitter orange extract, the plant synephrine comes from, and Burn carries 40 mg of synephrine, so stacking them doubles up on that too. The ISSN’s 2023 energy drink stand makes the same point about mixing caffeinated products: many combinations have never been studied, and indiscriminate use with other caffeinated drinks may lead to adverse effects. If pre-workout alone already rattles you, start with why pre-workout makes you jittery.
Can You Take a Fat Burner With a Stim-Free Pre-Workout?
Yes, and it is the cleanest way to have both. A stim-free pre-workout brings the pump and endurance ingredients without adding caffeine to the day.
Ninja Swole, sold as stim free with no caffeine on its label, lists 7000 mg of L-citrulline malate 2:1, 1500 mg of Nitrosigine, 3200 mg of beta alanine and 2500 mg of betaine, and no caffeine row. It does carry 300 mg of CellFlo6 green tea extract, the same ingredient as Burn, with no caffeine figure on the label. Burn plus Swole keeps the day’s labelled caffeine at about 360 mg. Picture one car on Ocean Drive: one stimulant behind the wheel, the pump riding shotgun, nobody fighting over the steering. How the two kinds of pre-workout differ is in pump vs stimulant pre-workout.
When Should You Take a Fat Burner Around a Workout?
On Burn days, Burn is your stimulant, so the timing question is really about when you train.
The ISSN notes the most common caffeine timing is 60 minutes before exercise. Caffeine’s half-life in adults is about 5 hours (drug label data), and in a 2013 study 400 mg taken even 6 hours before bed disrupted sleep. So:
| You train | Ninja Burn | Pre-workout |
|---|---|---|
| Early morning | 4 capsules about 60 minutes before you train | None needed; Ninja Swole if you want the pump |
| Midday or after work | 4 capsules in the morning | Ninja Swole, stim free |
| Late evening | 4 capsules in the morning | Ninja Swole, stim free |
| Rest day | 4 capsules in the morning, or a day off | None |
Before or after eating? Ninja Burn’s directions do not say. If capsules sit badly on an empty stomach, take them with breakfast.
What Should You Never Stack With a Fat Burner?
Anything else that brings stimulants. On a Burn day, cross these off:
- A stimulant pre-workout, an energy drink or an energy shot. Each draws on the same 400 mg.
- Coffee on top of a full serving. After about 360 mg, the room left under 400 mg is about 40 mg, roughly one 12-ounce green tea (37 mg, FDA).
- A second fat burner, or anything else with synephrine, bitter orange or rauwolscine.
- Alcohol. Ninja Burn’s own directions rule it out.
- Prescription medication without your doctor’s yes.
Coach’s Corner: The 10-Minute Warm-Up, Scoop Timed In
- Mix and drink: one scoop of Ninja Swole in 8 to 10 oz of water as you walk in, no rest. Sip it through the warm-up if your stomach is touchy.
- Bike or rower: 4 minutes easy to moderate, no rest. Finish warm enough for a light sweat.
- Goblet squat: 2 x 10 with a light dumbbell, 30 seconds rest. Elbows inside the knees, chest up.
- Band pull-apart: 2 x 15, 30 seconds rest. Arms straight, squeeze the shoulder blades together.
- Ramp-up sets of your first lift: 3 sets of 5, 3 and 1, building to your working weight, 60 to 90 seconds rest. Same bar speed on every rep.
Healthy adults: if you have an injury, pain, a heart condition, or you are new to training, check with your doctor before you start. Stop if it hurts.
The Fuel Plan
| Caffeine budget | 80 kg lifter | 100 kg lifter |
|---|---|---|
| Performance range (3 to 6 mg/kg, ISSN 2021) | 240 to 480 mg | 300 to 600 mg |
| FDA daily figure, most adults | 400 mg | |
| Ninja Burn alone (about 360 mg) | About 4.5 mg/kg | About 3.6 mg/kg |
| Ninja Burn plus Ninja Up (about 760 mg) | About 9.5 mg/kg | About 7.6 mg/kg |
| Ninja Burn plus Ninja Swole (about 360 mg) | About 4.5 mg/kg | About 3.6 mg/kg |
| Room left under 400 mg after Burn | About 40 mg, roughly one 12-ounce green tea (37 mg, FDA) | |
These are general numbers for healthy adults. With kidney disease, diabetes or any medical diet, ask your doctor or a registered dietitian.
Where Ninja Burn Fits
If you want a thermogenic and a pump on the same day, the stack is simple: Ninja Burn in the morning as your one stimulant product, and a stim-free pre-workout before you train. Four capsules carry the caffeine, Dynamine, synephrine and the thermogenic extracts with every dose printed, which is exactly why you could do this arithmetic before swallowing a single capsule. Try that with a proprietary blend.
Who it’s for: experienced stimulant users in a cutting phase who will let Burn be the only stimulant product in their day. Who it’s not for: beginners, the caffeine sensitive, anyone under 18, pregnant or nursing, anyone unwilling to drop the coffee and the stim pre-workout on Burn days, and anyone hoping for a weight-loss promise. We make none.
Ninja Burn: The Doses This Article Is About
Per serving of 4 capsules, straight from the label. The full label is on the product page.
| Caffeine Anhydrous | 200 mg |
| Infinergy™ (Dicaffeine Malate) | 150 mg |
| Caffeine Citrate | 100 mg |
| Dynamine™ (Methylliberine) | 200 mg |
| Synephrine | 40 mg |
| CellFlo6™ (Camellia sinensis) Leaf Extract (Green Tea) | 300 mg |
| Capsimax™ as Capsicum Fruit Extract (std. to 2%Capsaicinoids) | 100 mg |
Ninja Burn is $54.99 for 25 servings: $2.20 a serving, or $1.87 a serving on Subscribe and Save at 15% off. One form, capsules.
For the pump on Burn days, the stim-free partner is Ninja Swole, which Burn buyers already add to their orders: $2.00 a serving, or $1.70 on Subscribe and Save, in Bomb Pop, Rainbow Candy and Watermelon.
I start every morning with the fat burner during my prep. It has really helped me kick start my day. Perfect amount of caffeine and amazing other ingredients.
Absolutely loved this product. I took it and felt my core temperature go up and could feel the urge to go and do something instead of snacking. Once I did eat I was full and not craving more food.
Ninja Burn is a high-stimulant thermogenic. Per serving of 4 capsules the label lists 200 mg caffeine anhydrous, 150 mg Infinergy (dicaffeine malate) and 100 mg caffeine citrate, plus 200 mg Dynamine (methylliberine) and 40 mg synephrine. Not for anyone under 18, pregnant or nursing. If you have a heart condition or take medication, check with your doctor first. Do not stack it with coffee, energy drinks, pre-workout or any other caffeine, and do not take it with alcohol.
Frequently Asked Questions
Can I take a fat burner and pre-workout at the same time?
Only if the pre-workout is stim free. A serving of Ninja Burn is about 360 mg of caffeine once its three forms are converted, and a high-stim pre-workout like Ninja Up adds about 400 mg more, nearly double the FDA’s 400 mg a day for most adults.
How long after a fat burner can I take a stimulant pre-workout?
Not the same day. Caffeine’s half-life in adults is about 5 hours, so much of a morning dose is still working by the afternoon, and in a 2013 study 400 mg taken 6 hours before bed still disrupted sleep.
Should you take a fat burner before or after eating?
Ninja Burn’s directions say four capsules once a day and do not mention food. If capsules sit badly on an empty stomach, take them with breakfast.
What are the side effects of taking a fat burner with pre-workout?
The FDA’s signs of too much caffeine: a faster heart rate, palpitations, higher blood pressure, jitters, an upset stomach, nausea, headache and poor sleep. If you feel chest pain, a pounding or irregular heartbeat, or faint, stop and get medical help.
How do you safely add a fat burner to a fitness routine?
Count every caffeine source first, let the fat burner be the only stimulant product of the day, pair it with a stim-free pre-workout, take it early, and keep your training and protein in place. If you have a heart condition or take medication, check with your doctor before you start.
Next on the mission: how thermogenic supplements work, ingredient by ingredient. And when the arithmetic checks out for you, Ninja Burn is in the Close above.
Sources
- U.S. Food and Drug Administration. Spilling the Beans: How Much Caffeine is Too Much?
- DailyMed, U.S. National Library of Medicine. Caffeine citrate solution: drug label. (Caffeine base is one half of the caffeine citrate dose; adult half-life about 5 hours.)
- PubChem, U.S. National Library of Medicine. Caffeine (CID 2519). Molecular weight 194.19.
- PubChem, U.S. National Library of Medicine. Malic Acid (CID 525). Molecular weight 134.09.
- Guest NS, et al. International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition, 2021.
- Jagim AR, et al. International society of sports nutrition position stand: energy drinks and energy shots. Journal of the International Society of Sports Nutrition, 2023.
- Ratamess NA, et al. The Effects of Supplementation with p-Synephrine Alone and in Combination with Caffeine on Metabolic, Lipolytic, and Cardiovascular Responses during Resistance Exercise. Journal of the American College of Nutrition, 2016.
- Drake C, et al. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine, 2013.
- VanDusseldorp TA, et al. Safety of Short-Term Supplementation with Methylliberine (Dynamine®) Alone and in Combination with TeaCrine® in Young Adults. Nutrients, 2020 (funded by a grant from the ingredient’s distributor).
How we wrote this: we rewrote this page because people search Google for whether they can take a fat burner with pre-workout and how to add fat burners and thermogenics to a routine safely. We converted each caffeine form on the Ninja Burn and Ninja Up labels using the drug label and PubChem figures above, read the ISSN position stands and trials on PubMed and the FDA’s caffeine guidance, and checked every Ninja Burn dose against the product label. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
