Losing weight by reducing body fat is a challenging but achievable goal that requires commitment and consistency. Before putting too much hope in supplements for weight loss, it's essential to understand that no single ingredient or tablet will cause weight loss on its own.
If fat loss is your objective, you must establish a caloric deficit — consuming fewer calories than your body expends. Supplements work by supporting your efforts, not replacing them, so maintaining realistic expectations is key.
This deficit can be achieved through diet alone (reducing calorie intake), exercise alone (increasing energy expenditure), or, most effectively, by a combination of both.
Jump to:
- Understanding the Calorie Deficit for Weight Loss
- How Do Weight Loss Supplements Work?
- The Best Supplements for Weight Loss
- FAQs
Understanding Calorie Deficit for Weight Loss
A calorie deficit is the fundamental principle behind all successful weight loss, regardless of the diet or exercise plan you follow.
Your body has a total daily energy expenditure (TDEE), which is the number of calories you burn daily simply by existing, moving and exercising.
To lose weight, you must ensure your calorie intake (calories consumed) is consistently lower than your TDEE (calories burned).
This difference forces your body to tap into stored energy, primarily body fat, to cover the energy gap.
Supplements can help you maintain this necessary deficit in two primary ways:
Reducing Calorie Intake: By enhancing feelings of fullness (satiety) and controlling appetite, making it easier to eat less food. Boosting Energy Expenditure: By increasing the number of calories you burn during exercise or at rest (metabolism).
How Do Weight Loss Supplements Work?
Weight loss supplements can support your fat loss efforts through a variety of different mechanisms.
Ingredients in targets a specific aspect of the energy balance equation, helping you to stick to your calorie deficit goal.
Common mechanisms include:
Appetite Regulation: They increase feelings of fullness or slow digestion, which helps reduce overall food consumption. Thermogenesis: This involves increasing your body's core temperature, leading to a slight increase in calorie burning, even when resting. Fat Metabolism: They can help support the process by which your body breaks down and uses stored fat for energy. Energy and Focus: Ingredients that boost energy levels and mental focus can help you train harder and for longer, increasing calorie expenditure.
The Best Supplements for Weight Loss
Based on current scientific evidence, certain supplements have demonstrated a consistent ability to aid a calorie-restricted diet and exercise regime. We've ordered this list by descending strength of evidence to help you prioritise your choices.
1. Whey Protein
Protein is widely considered the single most effective supplement for weight loss due to its profound impact on satiety and metabolism.
When in a calorie deficit, adequate protein intake is crucial for preserving lean muscle mass, which is metabolically active and helps maintain a higher resting metabolic rate.
Whey protein is a fast-digesting, complete protein that delivers all essential amino acids needed for muscle repair and recovery.
Research consistently shows that higher protein consumption increases satiety more than carbohydrates or fat, helping you feel fuller for longer and naturally reducing overall calorie intake. In one double-blind 12-week study, greater weight loss, and significantly more body fat lost with less lean muscle, was seen in a group consuming a whey protein drink before meals while on a calorie-restricted diet.1
Additionally, the body burns more calories digesting protein compared to other macronutrients, a phenomenon known as the thermic effect of food (TEF).
Summary: Whey protein is the best weight loss supplement as it significantly increases satiety, preserves muscle mass in a deficit, and slightly boosts your metabolism (TEF).
2. Green Tea Extract
Green tea extract is a popular ingredient in fat loss supplements, primarily because it contains potent antioxidants called catechins, most notably epigallocatechin gallate (EGCG).
EGCG is thought to support fat metabolism by inhibiting an enzyme that breaks down norepinephrine, a hormone that signals fat cells to release fat for energy.
Systematic reviews and meta-analyses suggest that green tea extract can lead to modest but significant reductions in body weight, BMI, and body fat, particularly when combined with regular exercise.
In one study, the consumption of catechins was seen to have a positive effect for weight loss and weight maintenance.4
The combination of EGCG and the natural caffeine content often found in the extract is believed to produce a synergistic, thermogenic effect.
Summary: Green tea extract can support fat loss by enhancing fat metabolism and contributing to a small increase in calorie expenditure, especially when active.
3. Caffeine
Caffeine is one of the world's most consumed and well-studied stimulants, offering a direct route to boosting energy expenditure and performance.
It works by stimulating the central nervous system, which can increase the release of catecholamines like adrenaline and noradrenaline.
This action has two key benefits for weight loss:
Increased Energy Expenditure: Caffeine can enhance the process of fat oxidation and slightly elevate resting metabolic rate. Improved Performance: It can reduce the perception of effort during exercise, allowing you to train harder and for longer, increasing calorie expenditure.
Caffeine may also have a temporary appetite-suppressing effect, further supporting your ability to maintain a calorie deficit.
Summary: Caffeine supports weight loss by increasing energy, enhancing exercise performance, and slightly boosting thermogenesis and fat oxidation.
4. Glucomannan
Glucomannan is a natural, water-soluble dietary fibre derived from the konjac root, and is an effective non-stimulant appetite suppressant.
It has an exceptional capacity to absorb water, expanding significantly in the stomach to create a feeling of fullness (satiety).
This increased satiety helps reduce the likelihood of overeating at subsequent meals, which directly aids in maintaining a calorie deficit.
The European Food Safety Authority (EFSA) has recognised glucomannan's contribution to weight loss, provided it is consumed as part of an energy-restricted diet.
Summary: As a soluble fibre, glucomannan promotes satiety, occupies space in the stomach, and can help reduce calorie intake when taken before meals.
5. White Kidney Bean Extract (Phaseolus Vulgaris)
White kidney bean extract (WKBE) is a popular supplement for those looking to manage carbohydrate intake.
Its primary mechanism is the inhibition of the digestive enzyme alpha-amylase, which is responsible for breaking down complex carbohydrates into simple sugars.
By temporarily blocking this enzyme, WKBE can reduce the digestion and absorption of some starches, meaning fewer calories are absorbed from a carb-rich meal.
While the effects are modest, WKBE can be a useful tool for supporting a calorie-controlled diet, particularly when eaten with carbohydrate-rich meals.
Summary: WKBE may help reduce the absorption of starches by inhibiting the alpha-amylase enzyme, offering support for a calorie-restricted diet.
6. Omega 3 Fatty Acids
Omega 3 fatty acids, specifically EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), are essential fats with widespread health benefits.
While not a direct "fat burner," Omega 3s play a supportive role in overall weight management and metabolic health.
One study investigated whether appetite could be affected by omega 3 fatty acids when included in a calorie-restricted diet, and a positive relation between omega 3 and fullness was observed, suggesting it may have uses for weight maintenance.5
Furthermore, omega 3s are powerful anti-inflammatories, which is beneficial since chronic, low-grade inflammation is often associated with obesity and metabolic dysfunction.
Summary: Omega 3s are beneficial for overall metabolic health, may increase satiety, and reduce inflammation, supporting a healthy body environment for fat loss.
Other Supporting Supplements
While the focus remains on the core supplements for weight loss, other products can support your journey.
Multivitamins: When in a calorie deficit, it can be difficult to get all essential vitamins and minerals, so a high-quality multivitamin acts as a nutritional safety net. L-Carnitine: This compound helps transport fatty acids into the mitochondria, where they are burned for energy. Recent scientific data has indicated that L-carnitine also plays a role in preventing cellular damage from exercise stress, and supplementation can actually have benefits for training, competitions and recovery 6. BCAAs (Branched-Chain Amino Acids): A scientific review has shown emerging evidence that the metabolic roles of leucine (a BCAA) has some effect on weight loss, in addition to supporting muscle maintenance and recovery.3 BCAAs have also been shown to help regulate the body's insulin levels and play a large role in several different metabolic reactions.2
FAQs: Weight Loss Supplements
How much weight loss can I realistically expect from supplements?
Supplements are a tool, not a cure, and they typically result in modest, incremental weight loss benefits.
The majority of your weight loss will come from your consistent calorie deficit and exercise regime.
Expect them to enhance fat loss by around 5-15% on top of diet and exercise results, but not to cause weight loss on their own.
Which supplements work best together?
A synergistic approach focuses on targeting both sides of the calorie equation: appetite and energy expenditure.
A highly effective combination would be a whey protein shake (for satiety and muscle preservation) combined with green tea extract or caffeine (for energy and thermogenesis).
Adding glucomannan before meals would also compound the appetite-suppressing effect for maximum control over hunger.
Do I need to exercise for supplements to work?
You can lose weight through a calorie deficit created by diet alone, but supplements are significantly more effective when combined with exercise.
Supplements with caffeine and green tea extract are designed to enhance your performance and metabolism, which is most beneficial when you are physically active.
Even protein works best in conjunction with resistance training to ensure the weight you lose is fat, not muscle.
How long does it take to see results?
While you may feel the effects of stimulants like caffeine almost immediately (more energy), the measurable changes in body composition take time.
Consistent use of supplements, alongside a calorie deficit, usually requires 4-12 weeks of continuous effort before visible results are achieved.
Focus on non-scale victories like increased energy, better recovery, and controlled hunger in the initial stages.
Are there any safety concerns I should know about?
Most popular and well-researched supplements, such as protein, omega-3 and glucomannan, are safe for most healthy adults when taken at recommended dosages.
Stimulants like caffeine and green tea should be used with caution, especially if you are sensitive to caffeine or have any pre-existing conditions.
Always follow the recommended dosage and, as with any supplement, consult a healthcare professional if you are taking medication or have any underlying health concerns.
Take Home Message
Diet supplements are a powerful support system for your weight loss journey, but they are not a replacement for fundamental lifestyle changes.
Your success is built on the foundation of a consistent caloric deficit, achieved through a healthy, balanced diet and regular exercise.
By strategically incorporating high-quality supplements like whey protein (for satiety and muscle), green tea extract, and caffeine (for energy and metabolism), you can make the process easier and more efficient.
Consistency and commitment are the true keys to achieving and sustaining your fat loss goals.
Casey Walker is an experienced sports nutrition new product development technologist. He holds a Bachelor of Science in Sports and Exercise Science and a Master of Science in Sports Sciences and Physiology.
Casey’s scientific research area of expertise lies in the effects of dietary nitrates on sprint performance and exercise-induced muscle damage. He has also worked as a sports scientist for a medal-winning Paralympic track cyclist, with a goal of qualifying for the Rio 2016 Paralympics.
Find out more about Casey’s experience here.
In his spare time, Casey is a keen middle-distance runner with an interest in triathlon. He’s always looking out for the latest blends and supplements to improve his half-marathon time and recovery.
- Frestedt, J. L., Zenk, J. L., Kuskowski, M. A., Ward, L. S., & Bastian, E. D. (2008). A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study. Nutr Metab (Lond), 5(1), 8.
- Shah, S. H., Crosslin, D. R., Haynes, C. S., Nelson, S., Turer, C. B., Stevens, R. D., … & Svetkey, L. P. (2012). Branched-chain amino acid levels are associated with improvement in insulin resistance with weight loss. Diabetologia, 55(2), 321-330.
- Layman, D. K. (2003). The role of leucine in weight loss diets and glucose homeostasis. The Journal of nutrition, 133(1), 261S-267S.
- Hursel, R., Viechtbauer, W., & Westerterp-Plantenga, M. S. (2009). The effects of green tea on weight loss and weight maintenance: a meta-analysis. International journal of obesity, 33(9), 956-961.
- Parra, D., Ramel, A., Bandarra, N., Kiely, M., Martínez, J. A., & Thorsdottir, I. (2008). A diet rich in long chain omega-3 fatty acids modulates satiety in overweight and obese volunteers during weight loss. Appetite, 51(3), 676-680.
- Volek, J. S., Kraemer, W. J., Rubin, M. R., Gómez, A. L., Ratamess, N. A., & Gaynor, P. (2002). L-Carnitine L-tartrate supplementation favorably affects markers of recovery from exercise stress. American Journal of Physiology-Endocrinology and Metabolism.
