In 30 seconds
- First, the foundations: a deficit that brings your weight down by 0.5-1% a week, 2.3-3.1 g of protein per kilo of lean mass, strength training and good rest.
- CLA: in a meta-analysis of 18 trials, 3.2 g a day led to 0.09 kg more fat lost per week than placebo; in studies of 6 months or more, 1.3 kg more.
- L-carnitine: in 9 trials with 911 adults, 1.33 kg more weight loss than the control group.
- Protein and creatine have official claims. “Protein contributes to the maintenance of muscle mass.” “Creatine increases physical performance in successive bursts of short-term, high intensity exercise.” The beneficial effect is obtained with a daily intake of 3 g of creatine.
The fat-loss supplements with studies behind them are CLA and L-carnitine, with their figures compared with placebo. Protein and creatine add their official claims. Caffeine also has support, although we do not sell it. They all build on the same foundations: a deficit, protein, strength training and sleep.
This guide introduces them one by one, with what the studies found, when to take them and how to combine them in your day.
Before supplements
The foundations of your fat-loss phase, in four pieces
First, the foundations
Supplements work as support for a plan that is already under way. These are its four pieces, with where we explain each one in depth:
- A moderate deficit. Lose between 0.5 and 1% of your body weight a week: this is the pace recommended by the key review on fat-loss phases in natural bodybuilding to preserve muscle 1. Work out your calories with the calorie deficit calculator, or step by step in calorie deficit: how much to eat.
- High protein. In a deficit, the same review recommends 2.3-3.1 g per kilo of lean mass a day 1. You have the trials in protein in a calorie deficit.
- Strength training. Keep your main exercises and your intensity while you diet. What the studies say, in strength training and fat loss.
- Sleep. We explain what happens when you cut back on sleep in sleep and fat loss.
You have the full plan, with tables by body weight, in the fat-loss guide. From here on, we focus on the supplements.
The supplements at a glance
| Supplement | What is known | When to take it | Doses in the studies |
|---|---|---|---|
| CLA | 0.09 kg more fat lost per week than placebo; 1.3 kg in studies of 6 months or more | With meals | 3.2 g a day as the reference; 2.4-6 g in the long studies |
| L-carnitine | 1.33 kg more weight loss than the control group, in 9 trials | 30 minutes before training | 1.8-4 g a day |
| Protein | Protein contributes to the maintenance of muscle mass | Spread across 3-6 meals, including before and after training | 2.3-3.1 g per kilo of lean mass a day, including food |
| Creatine | Creatine increases physical performance in successive bursts of short-term, high intensity exercise. The beneficial effect is obtained with a daily intake of 3 g of creatine. | One scoop a day | 3 g a day |
| Caffeine (we do not sell it) | Useful effects when preparing for a fat-loss phase, according to the key review | Before training | EFSA limits: 200 mg at a time and 400 mg a day |
Sources: Whigham et al., 2007; Onakpoya et al., 2012; Pooyandjoo et al., 2016; Helms et al., 2014; Regulation (EU) No 432/2012; EFSA, 2015.
The first two are two classics of fat-loss phases. The next two have an official EU claim. And caffeine is the one many people already take without realising, in their coffee. Let us go through them one by one.
CLA compared with placebo
What the CLA studies measured
CLA: what the meta-analyses say
CLA, or conjugated linoleic acid, is a mixture of forms of linoleic acid with the double bonds arranged differently. It is found mainly in dairy products and beef 10, but in small amounts.
0.09 kg more fat per week
The key meta-analysis pooled 18 placebo-controlled trials. With 3.2 g of CLA a day, people lost 0.09 kg more fat per week than with placebo 2.
Two details from that study tell you how to take it 2:
- The more CLA, the greater the effect, within the doses studied.
- The effect grew almost linearly over the first 6 months.
A one-year trial
A one-year placebo-controlled trial followed 180 men and women with overweight, who ate normally. They took 3.4 or 3.6 g of CLA a day, depending on the form 3.
At the end, their fat mass was between 6.9 and 8.7% lower than in the placebo group. With the free fatty acid form, lean mass was also 1.8% higher 3.
Studies of 6 months or more
A second meta-analysis included only trials lasting 6 months or more, in people with overweight or obesity. Compared with placebo, it found 0.7 kg less body weight and 1.3 kg less fat 4. Those trials used between 2.4 and 6 g of CLA a day 10.
How to take it
- When: one softgel with each main meal, with a glass of water.
- For how long: EFSA considers 3-3.5 g of CLA a day for 6 months to be safe 5. That fits the length of a fat-loss phase.
You have all the data in CLA: what the studies say. And if you are a woman, the trials in women, including after the menopause, are in CLA in women.
L-carnitine: your pre-training companion
According to physiology studies, L-carnitine carries long-chain fatty acids into the mitochondria, where they are used to produce energy. Around 95% of the carnitine in your body is in your heart and muscles 6.
As a supplement, its figures come from a meta-analysis of 9 trials with 911 adults. Those who took it lost 1.33 kg more weight than the control group and lowered their body mass index by 0.47 points more 7. In 8 of those trials, 1.8-4 g a day was used, for 30 to 360 days 6.
The largest effects were seen in the shorter studies 7. That is why it makes sense for specific phases, such as your fat-loss phase. And if you do not exercise? We look at that in L-carnitine without exercise.
You have the rest of the studies, including those on recovery, in L-carnitine: what the studies say.
Protein: the foundation of your fat-loss phase
Its official claim fits a fat-loss phase perfectly: “Protein contributes to the maintenance of muscle mass” 8. And if you also want to build muscle, there is another: “Protein contributes to a growth in muscle mass” 8. A varied and balanced diet and a healthy lifestyle are important.
The key review's figures for a fat-loss phase 1:
- Per day: 2.3-3.1 g per kilo of lean mass.
- Distribution: across 3-6 meals.
- Around training: a serving of 0.4-0.5 g per kilo before and another after. If you weigh 75 kg, around 30-38 g in each.
The shake complements your meals: it is the simplest way to reach your figure when food falls short.
Creatine: the official claim
Creatine has one of the most widely known claims in sport: “Creatine increases physical performance in successive bursts of short-term, high intensity exercise”. The beneficial effect is obtained with a daily intake of 3 g of creatine 8.
What role does it play in a fat-loss phase? The key review places it among the supplements with useful effects during preparation, along with caffeine and beta-alanine 1. We explain it in creatine while cutting.
Caffeine in healthy adults
EFSA's limits, counting your coffee
Caffeine: keep count
We do not sell it, but it deserves its place: the key review also considers it useful when preparing for a fat-loss phase 1. What matters is not overdoing it. According to EFSA, for healthy adults 9:
- At a time: up to 200 mg, including less than 2 hours before intense exercise.
- Per day: up to 400 mg, adding up all sources.
- Pregnancy and breastfeeding: up to 200 mg a day.
Count coffee, tea, cola drinks and any pre-training supplement. You have the doses per kilo and its effect on sleep in caffeine and performance.
What about fat burners with stimulants?
Many fat burners are based on stimulants: caffeine, often together with synephrine, the stimulant in bitter orange 10. Their approach is different: stimulation.
Synephrine mimics adrenaline. In a study with 15 healthy adults, a single 54 mg dose raised heart rate and blood pressure for up to 5 hours 10. And caffeine can keep you awake and make you jittery, effects that intensify when it is combined with other stimulants 10.
CLA and L-carnitine, by contrast, are stimulant-free:
- You take them whenever you train, including in the evening, without worrying about your sleep.
- They do not add to the coffee you already drink.
- They combine with each other without stacking stimulants.
We compare each fat burner, ingredient by ingredient, in fat burners: which ones work, according to the studies.
How to combine them in a day
| Time | What to take |
|---|---|
| Breakfast | 1 CLA softgel with water. Your scoop of creatine (3 g), if you take it. |
| Lunch | 1 CLA softgel with water. |
| 30 minutes before training | 20 ml of L-carnitine, straight. |
| During long cardio | Nitrus Isotonic in 400-500 ml of water. |
| After training | A protein shake, if you do not reach your figure with food. |
| Dinner | 1 CLA softgel with water. |
On days when you do not train, take the L-carnitine with a meal.
Three rules to get the most out of them:
- Consistency. CLA is measured in weeks and months, not days 2. Take it every day throughout your fat-loss phase. What to expect month by month is in how long CLA takes to work.
- The dose on the label. No more and no less.
- Foundations first. A deficit, protein, strength training and sleep: supplements build on top of these.
Common mistakes
- Putting the cart before the horse: supplements work on top of a deficit; the deficit comes first.
- Taking them on and off: CLA studies measure its effect over weeks of daily use 2.
- Adding stimulants without counting your coffee: EFSA sets the limit at 400 mg of caffeine a day 9.
- Falling short on protein: just when you need it most.
- Looking only at the scales: also pay attention to your waist and how your clothes fit.
If you are pregnant or breastfeeding, take medication or have diabetes, check with your doctor first.
Frequently asked questions
Which supplements help with fat loss?
Two classics of fat-loss phases, with figures from the studies, are CLA, with 0.09 kg more fat lost per week than placebo, and L-carnitine, with 1.33 kg more weight loss than the control group. Add protein: “Protein contributes to the maintenance of muscle mass.”
Which supplements should you take to lose fat and build muscle?
Protein and creatine have official claims. “Protein contributes to a growth in muscle mass.” “Creatine increases physical performance in successive bursts of short-term, high intensity exercise.” The beneficial effect is obtained with a daily intake of 3 g of creatine. For the fat side, CLA and L-carnitine are two classics.
How long do you need to take CLA to see results?
Studies measure it in weeks and months: in the key meta-analysis, the effect grew almost linearly over the first 6 months. EFSA considers 3-3.5 g a day safe for 6 months, so the practical approach is to take it every day throughout your fat-loss phase.
Are there stimulant-free fat burners?
Yes. CLA and L-carnitine contain no caffeine or synephrine, so you can take them whenever you train without adding stimulants to your coffee. Caffeine can disturb sleep and cause jitteriness, especially when combined with other stimulants.
Can you take CLA and L-carnitine together?
Yes. You take them at different times: CLA, one softgel with each main meal, and L-carnitine, 20 ml 30 minutes before training.
Sources
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11(1):20. View publication
- Whigham LD, Watras AC, Schoeller DA. Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr. 2007;85(5):1203-1211. View publication
- Gaullier JM, Halse J, Høye K, Kristiansen K, Fagertun H, Vik H, Gudmundsen O. Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans. Am J Clin Nutr. 2004;79(6):1118-1125. View publication
- Onakpoya IJ, Posadzki PP, Watson LK, Davies LA, Ernst E. The efficacy of long-term conjugated linoleic acid (CLA) supplementation on body composition in overweight and obese individuals: a systematic review and meta-analysis of randomized clinical trials. Eur J Nutr. 2012;51(2):127-134. View publication
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Statement on the safety of the «conjugated linoleic acid (CLA)-rich oils» Clarinol® and Tonalin® TG 80 as novel food ingredients. EFSA Journal. 2012;10(5):2700. View publication
- Office of Dietary Supplements, National Institutes of Health. Carnitine: fact sheet for health professionals. View publication
- Pooyandjoo M, Nouhi M, Shab-Bidar S, Djafarian K, Olyaeemanesh A. The effect of (L-)carnitine on weight loss in adults: a systematic review and meta-analysis of randomized controlled trials. Obes Rev. 2016;17(10):970-976. View publication
- Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods. View publication
- EFSA. Caffeine. Topic page on the European Food Safety Authority's scientific opinion on the safety of caffeine, 2015. View publication
- Office of Dietary Supplements, National Institutes of Health. Dietary supplements for weight loss: fact sheet for health professionals. View publication
Information based on published studies. It does not replace the advice of a doctor or registered dietitian. The results describe what was measured in each study, not the properties of any specific product.
