Caffeine is the most commonly available weight loss aid and not everyone seems to know it, a core ingredient in many fat burners, there are a lot of myths around caffeine and weight loss, but if used correctly your morning coffee can be more than effective at helping you lose weight.
Is Caffeine Good For Weight Loss?
The short answer to this is yes, and the long answer is that it depends on how you expect it to work. Caffeine has been backed in multiple studies for weight loss and it has 3 key mechanisms as to it’s function. However, it’s not just going to make you lose weight by itself, at least not in any substantial manner.
The 3 mechanisms main mechanisms for caffeine aiding weight loss are:
- Appetite suppression
- Raising NEAT (how much you move through the day unrelated to purposeful exercise)
- Thermogenesis (how many calories you burn without moving)
The first 2 are the most effective, with thermogenesis coming far behind in third, a lot of weight loss aids will substantially over promote how effective this is and this has been tested with both caffeine pills and drinking coffee for weight loss.
There is one other major benefit of caffeine for weight loss and that’s caffeine helps focus and energy, this may not seem important, but when people are in a caloric deficit (the only way to lose weight is by eating less calories than you use), it can become hard to focus, and people can become irritable and struggle to do their day to day tasks as efficiently, leading people to give up on dieting. In short caffeine helps deal with the common side effects of dieting.
This is also part of what happens with NEAT, when people work out, especially in a caloric deficit the amount we move throughout the day drops subconsciously. Caffeine’s stimulating effect helps reduce this drop. Of course, if you simply have the exact same amount of caffeine that your bodies used to it’s not going to change much.
How Well Does Caffeine Suppress Appetite?
It depends on the context of when you have the caffeine, if it’s taken just before a meal then it tends to be effective with studies showing that even 1mg of caffeine per 2lbs the subjects weighed, reduced caloric intake under double blind monitored conditions.  Although 1mg of caffeine is a relatively low amount, and 3mg was more effective. This study also showed that the effects were only short term, and didn’t last throughout the day. This would suggest that the effect of caffeine is similar to glucomannan and it only works if you have it before you prep your food. Overall the studies generally show that drinking coffee 30 mins to 3 hours before a meal makes you eat less, and longer than that showed a relatively minimal difference, although it showed that caffeine as an appetite suppressant still had some effect. 
How Else Does Caffeine Help You Lose Weight?
Due to it’s properties as a stimulant effective at keeping you moving when on a calorie restricted diet, as we’ve already mentioned multiple studies show that we move less when we’re in a calorie restricted diet. This means that you’ll burn less calories through the day.  Caffeine gives you energy thus mitigating that effect, making it particularly useful whilst dieting.  On top oof this caffeine can help you lose weight by increasing your physical performance when working out, this one is pretty self explainitory move more during a work out, burn more fat.
Why Coffee Doesn’t Help You Lose Weight?
Usually speaking if you’re drinking coffee and not seeing any benefits from it, the it’s likely that you’re adding more calories than you're butning from consuming caffeine helps you burn, there’s a few ingredients that sneak in way more calories than you’d expect. The same applies when it comes to other caffeinated beverages.
Whilst black coffee is normally only around 30kcal, creamer for example can add anywhere between 35-50 kcal, add just 2 spoons twice a day and you’ve added 200kcal’s a day to your intake. This can be enough to take you out of a calorie deficit if you’re not careful, meaning that you won’t lose weight.
Sugar actually isn’t quite as bad as creamer, coming in at only 16kcal per teaspoon. Although if you’re using coffee for weight loss, best to use sweetener. The same applies to syrups.
As a result of these stealth calories, caffeine pills tend to be the more effective option. Although appetite suppression effects are slightly better when ingested as coffee.
What About Tea?
Whilst Green Tea does contain caffeine, it’s generally of a lower amount that will really help with weight loss, there are some other benefits of green tea. And you can read more about it here.
Caffeine Weight Loss Through Diuretic Properties
Caffeine is also a diuretic as a result it can show early results that are not necessarily relevant to long term weight loss. Although, the long term fat burning effects are still positive.
Does Combining Glucomannan And Caffeine For Weight Loss Increase Efficacy?
There are a number of weight loss aids that can be effective for appetite suppression, with glucomannan  and caffeine being the most well backed. Combining them isn’t always particularly effective, but do to the method in which these two work, they interact quite well. Glucomannan swells 50X larger in the stomach, making a 2000mg dose about the size of a bagel. Mixing caffeine and glucomannan an hour before food is very effective at reducing caloric intake.
How much caffeine for weight loss?
As we’ve previously mentioned 1-3mg/kilo of body weight (a kilo is 2.2lbs) is notably effective at reducing food intake if taken at the right time. This would be about 80-300mg per serving, although 1mg was effective, if you’re trying to figure out how much coffee for weight loss you need, for context a double espresso is about 150mg of caffeine making it more than viable for most people. Filter coffee is about 96mg, meaning it’s on the low side and a single shot americano is probably a bit too low. But, if you want to use coffee for weight loss, then you’re best getting a double shot in an americano or a double espresso and having it 30 mins to a few hours before you eat. Not only will it help you stick to your diet, but keep you moving, meaning that you won’t drop your calorie burn, so it can help you lose weight more efficiently.
Note: Generally speaking it's not recommended to have more than four cups of coffee per day.
1 - https://pubmed.ncbi.nlm.nih.gov/30033159/
2 - https://pubmed.ncbi.nlm.nih.gov/28446037/
3 - https://pubmed.ncbi.nlm.nih.gov/12468415/
4 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6467726/
5 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3892933/