Does ‘fasted’ cardio burn body fat? this is what science says

Concept of fasting every few years Exercise Training is all over social media.

Fasted training refers to exercising in the morning before eating breakfast.

Fans will claim this is the most effective way to lose body fatOpponents say it’s a terrible idea and will make you gain weight.

Who is right and what does the research evidence say?

Where did the idea come from?

Proponents say that fasted exercise will lead to better changes in body composition – the ratio of lean mass (muscle), bone, and fat. Specifically, they say that fasted exercise leads to fat loss.

Positive changes in body composition can occur through loss of fat mass, while either maintaining or gaining lean mass. Or even through gaining lean mass in the absence of any loss of body fat. All these can be considered positive.

The idea that fasted exercise causes such positive changes in body composition stems from research that shows that exercising after eating versus exercising before eating affects metabolism differently.

Aerobic exercise in a fasted state causes you to burn more fat as fuel when measured in the same time frame (what researchers will call “fat oxidation”). So it wasn’t a huge leap to assume that this would lead to long-term fat loss.

However, my team’s 2017 systematic review showed that fasted exercise training programs do not translate into long-term differences in body fat loss.

This discrepancy between fat burned as fuel during exercise and changes in body fat over the long term has often been misunderstood.

This apparent contradiction may be based on the fact that the body begins to find ways to compensate. Fat burning decreases once you eat, and people who have exercised hard may expend less energy overall during the day.

In exercise science, it is actually very common to find that short-term effects do not always translate into long-term effects.

For example, intense short-term exercise can have negative effects on your health. immune system For now, but regular exercise can really have a positive effect in the long run.

What happens if you eat right before or after your workout?

Eating foods rich in carbohydrates and protein when you exercise is likely to help with performance during your next exercise session.

However, whether that meal is eaten before or after your workout, it has limited impact.

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Interestingly, research has shown that increasing the proportion of food you eat in the morning – and in particular, eating more protein – may help improve body composition and increase weight loss,

However, this timing is not in relation to exercise, but in relation to when you eat during the day.

What about game performance?

It is quite clear that eating before exercise improves performance in activities lasting more than 60 minutes but has little effect on performance in activities of shorter duration.

This is also evidenced by the lack of elite athletes endorsing fasted exercise. A survey completed by nearly 2,000 endurance athletes showed that non-professional athletes are more likely to exercise faster than professional athletes.

What about strength training?

So did you notice a difference in muscle strength, size, and body composition in response to doing resistance training (like weight lifting) while fasting versus when you fasted and when you ate? Unfortunately, research is limited and of low quality.

The limited evidence so far suggests it doesn’t matter.

A recent randomized controlled trial also found no difference in strength, power or lean body mass when resistance training was performed twice a week for 12 weeks either fasting or after eating.

What are the possible drawbacks?

Fasted training can make you feel really hungry after exercise, which may lead to poor food choices.

Some people may also get headaches and nausea when they try to exercise while fasting. However, this is not the universal experience; Social media is full of people who say that exercising while fasting makes them feel great.

In short, there is no clear winner.

Evidence does not support the superiority of fasted exercise for weight loss or sports performance.

However, the evidence also does not show that it causes problems in many scenarios (except perhaps for specific sports performance).

So if you’re pressed for time and skipping breakfast gives you the opportunity to get out and go for a run or workout, then do so. Don’t worry too much about the result.

But if you want to avoid going to the gym because of the thought of exercising on an empty stomach, then have some breakfast before going. Rest assured that this will not work against your goals.

Exercise fads and health tricks come and go, but the only thing supported by solid and consistent evidence is exercise.

Just doing it is what matters most.

Not the time of day, not the exact choice of exercise, not even the exact amount – and certainly, not if you have or haven’t eaten anything before exercising.