Fat Loss Supplements: A Dietitian’s Guide
- Serena Benali, Registered Dietitian
- 32 minutes ago
- 4 min read
Written and medically reviewed by Serena Benali, Registered Dietitian. Published January 19, 2026.
Before You Spend Another Dollar on “Fat-Burners”
If you’ve ever searched for “best fat-loss supplements,” you’ve likely been met with bold promises, slick marketing, and a sea of conflicting advice. From metabolism boosters to appetite suppressants, the supplement world can make it seem like one capsule stands between you and your goals.
But here’s what we, as dietitians, want you to know:
No supplement on its own causes fat loss.
Real fat loss happens through consistent lifestyle habits - nourishing foods, regular movement, stress management, and sleep. Supplements can play a supportive role, filling small nutritional gaps or giving a gentle nudge to metabolism, but they are never the main driver of change.
That said, some supplements do have research behind them — not as magic bullets, but as tools that can complement a well-rounded nutrition plan. Let’s take a closer look at which ones are backed by evidence, and which might not live up to the hype.
1. Fibre: The Foundation of Appetite Regulation
If we had to choose a supplement most people overlook but probably need, it’s fibre. Despite its simplicity, fibre can be one of the most powerful tools for appetite control and digestive health.
Research consistently shows that increasing dietary fibre supports satiety, reduces cravings, and promotes steady blood-sugar control, all essential when working toward body composition goals.
You can get fibre naturally from:
Vegetables, fruits, and legumes
Oats, barley, and other whole grains
Chia, flax, and psyllium husk
If you struggle to meet the daily recommendation of ~25–38 g, a soluble fibre supplement (like psyllium or partially hydrolyzed guar gum) can help. Start small with 1 teaspoon per day and build gradually to avoid bloating or discomfort.
Why it matters: Fibre helps you feel full longer, slows digestion, and supports a healthy gut microbiome — all of which contribute to more balanced eating habits over time.
2. Protein: More Than Just a Gym Thing
Protein often gets framed as a “muscle” nutrient, but it’s equally crucial for metabolism and fullness.
High-protein diets have been shown to preserve lean muscle during weight loss and help regulate hunger hormones like ghrelin and peptide YY. Essentially, protein keeps you satisfied longer, which makes it easier to avoid unintentional overeating.
If you find it difficult to hit your protein goals through food alone, a protein supplement can be a convenient bridge.
When choosing one:
Aim for 20–30 g protein per serving
Check for minimal added sugar or artificial sweeteners
Choose the type that fits your needs - whey (fast digesting), casein (slow digesting), or plant-based blends (pea, soy, rice)
Pro tip: Using protein strategically like including it at breakfast or after workouts, can stabilize energy and support recovery while keeping cravings in check.
3. Caffeine: Effective, but Use with Caution
Caffeine is one of the most studied and effective ergogenic aids — meaning it enhances performance and alertness. It can temporarily increase energy expenditure and improve workout performance, which indirectly supports fat-loss efforts.
However, caffeine’s benefits come with caveats:
The ideal range is 3–6 mg/kg of body weight, or roughly 200–400 mg per day for most adults.
Going beyond that can cause jitters, anxiety, insomnia, and elevated heart rate.
The half-life of caffeine is 5–6 hours, so consuming it late in the day can easily disrupt sleep, which ironically makes fat loss harder.
Skip “fat burner” supplements that rely heavily on stimulant combinations; these often provide little more than an expensive caffeine hit and a racing heart.
If you use caffeine, treat it as a tool — not a crutch. Quality sleep, hydration, and nutrition are your true energy sources.
4. Green Tea Extract (EGCG): Small Effect, Big Hype
Green tea has long been marketed for its “metabolism-boosting” properties. The active compound, EGCG (epigallocatechin gallate), has been shown in some studies to slightly increase thermogenesis - the body’s calorie-burning process.
But context matters:
The effect is small — roughly 3–4% increase in energy expenditure.
Benefits are most noticeable when paired with caffeine and an active lifestyle.
High-dose supplements have occasionally been linked to liver stress, so moderation is key.
If you enjoy tea, aim for 2–3 cups daily. If using a supplement, look for a standardized extract providing 250–500 mg EGCG and always take it with food.
Bottom line: Green tea won’t melt fat away, but it can be a gentle, antioxidant-rich addition to a healthy routine.
5. “Promising” Supplements — Use with Caution
Some supplements show early promise, but the research is still developing.
5-HTP:
May affect appetite regulation through serotonin pathways, but data is limited and potential interactions with antidepressants are a concern.
L-Carnitine:
In theory, supports fat transport into cells for energy, but studies show minimal real-world fat-loss impact.
CLA (Conjugated Linoleic Acid):
Animal studies looked promising, but human trials show inconsistent results and possible gastrointestinal side effects.
Probiotics:
Gut health plays a role in weight regulation, but the effect depends heavily on the strain - not all probiotics are equal.
What Supplements Can’t Do
Even the most evidence-backed supplements can’t fix an inconsistent routine, chronic stress, or poor sleep.They work best as a support system, not as the centrepiece of a fat-loss strategy.
Be skeptical of any product claiming:
“Rapid fat melting”
“Targeted belly fat loss”
“Metabolism reset”
Fat loss comes from a consistent calorie deficit supported by nutrient-dense foods, physical activity, and rest - not from a bottle.
Key Takeaways:
Supplements like caffeine and green tea extract can temporarily increase fat oxidation (your body’s use of fat as an energy source).But that doesn’t necessarily mean fat loss, because total body fat only decreases when you’re in an overall energy deficit.
Others, like fiber and protein, make that deficit easier to maintain by controlling hunger and stabilizing blood sugar.
Supplements can assist the process but none can activate fat loss without the foundational habits in place: balanced nutrition, energy deficit, activity, and sleep. Smart supplementation is about strategy, not shortcuts. Focus on food first, use supplements to fill specific gaps, and rely on evidence over marketing.
If you’re curious about whether certain supplements fit your needs, we can help you interpret the science and apply it to your real life. At In Good Nutrition, our dietitians specialize in evidence-based nutrition for real people — no gimmicks, just guidance that works for you.
👉 Book a session today to build a plan that supports your goals safely and sustainably.
Disclaimer: This article is for educational purposes only and does not replace individualized medical or dietetic advice. Always consult a healthcare provider before starting new supplements.
