Overweight and obesity is becoming a natural problem, not just a natural problem, but also a healthy one, as the scale is already global. Obesity is one of the main causes of increased mortality and morbidity from conditions such as diabetes and heart disease.

There is a direct link between weight loss and improvement in health. The main methods of weight loss are and will always be most movement and proper nutrition.
There are, however, a number of supplements that are said to help burn fat. The most popular category of supplements for this purpose are thermogenic fat burners, and the most famous thermogenic is caffeine.



It is also known as energy and stimulant to increase strength and power. A major systematic review and meta-analysis have been published in 2018 that collects all scientific information on the effect of caffeine on fat burning.
 
What is being explored?

A large systematic review gathers all studies on the caffeine's effect on weight, BMI and subcutaneous fat percentage. Only placebo-controlled studies with random selection were collected. Both isolated caffeine and coffee are tested. The review follows all PRISMA standards.



The final analysis includes 13 studies and 606 participants. Thirteen of the studies reported weight results, 6 for BMI and 11 for subcutaneous fat. The duration of the tests ranges from 4 to 36 weeks (mean 12 weeks), with doses ranging between 60-720 mg caffeine (average 360 mg). Three of the studies tested isolated caffeine, and 10 used a coffee drink.

Scientists create subgroups according to criteria such as:

• Studies up to 12 weeks and those lasting over 12 weeks
• Geographical location (the US and other territories)
• Gender
• Caloric Restrictions

According to Kotran's criteria, the systematic review is characterized by a low risk of inaccurate results.



What is it established?

Caffeine significantly lowers all indicators - total body weight, BMI and subcutaneous fat percentage, with dose-dependent efficacy. Each extra milligram of caffeine is associated with 22% better weight gain, 17% better BMI results and 28% better outcomes for subcutaneous fat.

The results show that a positive result is seen in absolute subgroups, and caffeine effectiveness is unaffected by duration of intake, geography, sex and caloric restriction.



What exactly does the review tell us?

The results of the study confirm that caffeine helps weight loss and fat burning.
Of course, some remarks must also be made. The systematic review can not provide an answer for the optimal caffeine dose as well as the actual percentages of efficacy. The results show that each subsequent milligram per day may increase weight loss by 22%, but no exact figures are given because this may mean 10kg or 100g.

If the figures in some of the individual studies are more detailed, then more specific information can be found. For example, one study found that a combination of caffeine and ephedrine resulted in a weight loss of 3.9kg compared to placebo. Another study showed that a combination of caffeine and ephedrine resulted in a 1.5 kg weight loss over a 12-week period.



A second case in the systematic review is the placement of caffeine and coffee in one category, and they are, in fact, far from the same. Separately, in 10 of the studies, caffeine is combined with another ingredient. Namely, studies using coffee show the worst results.
A third case study is a large heterogeneity in individual studies.

There are significant differences in the doses administered, the duration and especially the subjects. For example, in one of the most positive tests, a large dose of caffeine per day (300-600 mg) with ephedra lasting 20 weeks was used and the subjects were 32 overweight people. It is clear that this result can not be attributed to average individuals or athletes.

The most important conclusion is that these results can not be applied to the real world. This, of course, does not mean that caffeine has no benefits.



The big picture

It has been found that caffeine affects some key mechanisms that are associated with weight loss. These include increasing energy expenditure and increasing oxidation of fatty acids. Apart from these two mechanisms, caffeine significantly increases strength and endurance, helping to increase calorie expenditure during exercise.

Caffeine increases relatively little energy expenditure. According to the tests, the effectiveness is 2-3% increased expenditure within 2-3 hours after intake. This can be converted to 150 kcal per day in a comparatively active individual with an average subcutaneous fat percentage or 80 kcal in an overweight.

Interesting is the fact that effectiveness is decreased when increasing the percentage of subcutaneous fat.



Caffeine also enhances the lipolysis and conversion of ester fatty acids into free fatty acids. This process is called "release" of fat. Thus, one study found that taking 10 mg of caffeine per kilogram of body weight strengthens the process twice! Caffeine, however, significantly increases the release of fat, but only 24% of it is oxidized. This percentage may increase if the process is combined with training.

Caffeine can have its benefits, but they are not universal. Exact percentages and doses are yet to be established. Until then, you can safely take your thermogenesis without forgetting that weight loss is the right nutrition and physical activity.