Caffeine for Fat Loss

Caffeine, the world’s most consumed psychoactive substance, may have mild weight loss benefits.

Caffeine is typically ingested as part of coffee or tea by billions of people to promote wakefulness and brain activity. However, caffeine may also be slightly effective for burning fat, through several modes of action:

• Increasing fat oxidation (the body’s usage of fat for energy)
• Increasing energy expenditure through its thermogenic (heat-generating) effect
• Enhancing exercise performance via vitality and focus benefits

Overview

Typically ingested in the form of coffee or tea, caffeine is the most widely consumed psychoactive chemical in the world. Used as part of the morning ritual by billions of people, caffeine has also been embraced in the workplace as a way of promoting brain activity and clarity.

As a result, caffeine has seen a massive amount of research into all of its potential benefits, which range from lower risk of developing type 2 diabetes to staving off Alzheimer’s. Caffeine is mainly used as a stimulant to promote wakefulness, alertness, and mental activity. While useful in these areas, it is not a true nootropic.

Caffeine has also been heavily studied as a possible weight loss aid. Some studies show that caffeine may have mild benefits for burning fat.

Caffeine’s Possible Fat-Burning Bio-Activities

Enhances Fat Oxidation

The mechanism behind this effect is complex, but scientists believe it is achieved by caffeine inhibiting certain enzymes such as phosphodiesterase, which leads to a rise in the levels of the hormone norepinephrine and the messenger molecule cyclic adenosine monophosphate (cAMP), which in turn increase fat oxidation.¹ Additionally, caffeine may affect certain receptors in fat cells, thereby enhancing their lipolysis (breakdown of fat).²

Boosts Energy Expenditure

Caffeine is believed to boost energy expenditure (how many calories you burn) by anywhere from 3% to 16%, depending on the dose taken.³ This mechanism is believed to function similarly to the fat oxidation effect, in addition to an increase in lactate and triacylglycerol production and increased tone of vascular smooth muscle.⁴

Supports Peak Physical Performance

Caffeine could act as an ergogenic aid – a compound that improves physical performance. Caffeine may increase exercise enjoyment, decrease perceived exertion and fatigue, and also make you feel more focused and energetic. As a result, you are more likely to work out with higher intensity and longer duration after ingesting caffeine. These effects are believed to result from caffeine acting on the central nervous system, where it inhibits adenosine, a neurotransmitter responsible for making you feel sleepy, while increasing serotonin and dopamine – two neurotransmitters associated with happiness and well-being.⁵ Caffeine may also be particularly helpful for endurance exercise by enhancing muscle contraction.⁶

Research

Human Research

Human trials of caffeine as a fat burner report mild benefits, although some studies showed no apparent effect. Furthermore, the large majority of studies are short in duration, so it is difficult to say whether the effect is maintained over a long period of time.

Caffeine 400 mg may have a notable thermogenic effect which can in turn reduce body fat

Six healthy male and female participants followed 4 different experimental conditions in random order: taking placebo and 100, 200, 400mg caffeine. The caffeine was found to increase energy expenditure in a linear manner, meaning that the 400mg dose had a proportionally stronger effect than 200 or 100mg.

• The researchers concluded that “The thermogenic effect of caffeine may reduce body fat stores in coffee drinkers if energy balance is not maintained by an increased energy intake”⁸

Caffeine 6mg/kg bodyweight may reduce calorie intake in overweight/obese individuals

The goal of this study was to see if caffeine had an effect on dietary intake. Sixteen normal weight and 17 overweight/obese individuals participated in 3 separate trials: they ate breakfast along with 200 ml of coffee with 3 or 6 mg caffeine/kg bodyweight, or water.

Normal weight individuals did not experience any changes, but the overweight/obese group ate 550 fewer calories for the rest of the day after taking 6 mg/kg caffeine.

• The researchers concluded that “there was no effect of coffee on dietary intake and appetite related feelings in normal-weight individuals; however, in overweight/obese coffee was found to exert an effect as consumption of a moderate amount in the morning, providing 6 mg of caffeine/kg body weight (equivalent to two to four cups), significantly reduced energy intake in the lunch, compared to a lower or no intake, and this effect was maintained during the rest of the day”⁹

Caffeine 3 mg/kg had no effect on energy intake or appetite in healthy men

This study recruited 16 men who on 3 separate occasions received breakfast along with 200 ml of either caffeinated, decaffeinated coffee, or water. Coffee was found to not have any apparent effect on how much the men ate or how hungry they felt, which may be explained by them being healthy and already moderate coffee drinkers

• The researchers concluded that “coffee, providing 3 mg of caffeine/kg body weight, was found to prevent morning cortisol concentrations from falling; no significant acute or immediate effects on energy intake, appetite, or inflammatory markers were observed¹⁰

Caffeine 10mg/kg may stimulate weight loss by increasing energy expenditure

Eight healthy men were given a placebo and 10mg/kg caffeine at separate times. The trial found that caffeine increased energy expenditure by up to 13% for several hours. Lipid turnover and oxidation were also increased – two measures of how the body is using fat for energy. The researchers suggest that caffeine achieves this by stimulation of the sympathetic nervous system.

• The researchers concluded that “the results of the present study show not only that caffeine stimulates resting energy expenditure but that this increased cellular thermogenesis is accompanied by an increase in fatty acid turnover and lipid oxidation”¹¹

Caffeine 5 mg/kg bodyweight had no effect on energy expenditure in healthy men

Thirty physically-active, normal-weight men followed two protocols: caffeine 5mg/kg bodyweight daily for 4 days, and later placebo for the same duration. Unlike the above study, this trial did not find any significant effect of caffeine on energy expenditure.

• The researchers concluded that “the beneficial role of caffeine ingestion as a strategy to increase thermogenesis and improve weight management may be questionable”¹²

Caffeine 6 mg/kg of bodyweight may improve weight loss effect of exercise

This study wanted to see the impact of caffeine on energy balance in combination with exercise. At its most basic level, energy balance is the equation that determines whether we gain or lose weight – the difference between how much energy we take in by eating, and how much we lose through bodily functions. The 14 non-obese participants completed 3 experimental conditions a minimum of 3 days apart: a resting control (no exercise), an exercise trial plus placebo (EX), and exercise plus caffeine 2x3mg/kg (EX+CAF). In comparison to EX, EX+CAF had slightly higher energy expenditure and fat oxidation (a measure of how much fat is being burned by the body). No significant difference was found in energy intake and perception of hunger between EX and EX+CAF. Lastly, participants noted that exercise during EX+CAF was less difficult and more enjoyable.

• The authors concluded that “The results of this study indicate that consuming caffeine before and after a bout of moderate exercise increased EE and fat oxidation while improving exercise enjoyment…While the increases observed in EE and fat oxidation compared with a normal exercise bout were relatively small, their effects over time could be important for weight maintenance and/or weight loss”¹³

Increased caffeine intake was associated with slightly lower weight gain over 12 years

This study is unique for its large scope – a total of 18,417 men and 39,740 women were assessed over a period of 12 years to examine the relationship between their caffeine consumption and weight. The trial found that an increase in caffeine intake was associated with a slight reduction in weight gain.

• The researchers concluded that “an increase in caffeine intake was associated with a smaller weight gain over 12 y of follow-up”¹⁴

Dosage Notes

Judging from research studies, the dosage that best combines effectiveness and safety is about 200-400 mg caffeine per day, which amounts to about 4 cups of brewed coffee. Taking more than 500-600 mg greatly increases the likelihood of side effects.¹⁶

Side Effects

Caffeine does not usually cause problems, unless a large dose is taken. Common side effects include insomnia, shakiness, irritability, headaches, dehydration, and abnormal heartbeat.¹⁷ Notably, some of the jitters associated with caffeine intake may be eased by stacking it with L-Theanine, a nootropic compound found in green tea.

Available Forms of Caffeine

• Plain caffeine: The form of caffeine naturally found in coffee, tea, and chocolate, added to soft drinks, and many other foods.
• Caffeine anhydrous: This is the waterless form of caffeine typically used in dietary supplements. It is advertised as being stronger and easier to absorb than plain caffeine.

References