Fasting has become one of the most popular dietary approaches for weight management and metabolic health.
Research suggests that intermittent fasting may support weight loss and improve several markers of metabolic health, including blood sugar regulation, cardiovascular risk factors and inflammation.12
However, many people wonder whether drinking alcohol affects fasting.
This article explains what current research says about alcohol and fasting.
How alcohol affects fasting
If your goal is weight loss, alcohol may reduce some of the benefits of fasting.
Alcohol temporarily suppresses fat oxidation because the body prioritises metabolising alcohol before carbohydrates and fat. Studies have also shown that alcohol may increase appetite and lead to greater energy intake during meals.34
Alcohol is also energy dense, providing approximately 7 kcal (29 kJ) per gram, making it the second most energy-dense macronutrient after fat.5
For example, one standard alcoholic drink may contribute around 100–150 calories, depending on the beverage and serving size. Regular alcohol consumption can therefore make it more difficult to maintain the calorie deficit needed for weight loss.6
Heavy or frequent alcohol intake is also associated with increased inflammation, liver disease and poorer metabolic health, potentially counteracting some of the health benefits associated with intermittent fasting.78
Finally, because alcohol contains calories, consuming it during your fasting window technically breaks a fast.
Summary
Alcohol may reduce some of the weight-management benefits of fasting by suppressing fat burning, increasing appetite and adding extra calories. Excessive alcohol intake also increases the risk of inflammation and liver disease.
Can you fast and still enjoy alcohol?
Drinking alcohol occasionally doesn't mean you can't practise intermittent fasting.
If you choose to drink alcohol, it is generally better to consume it during your eating window rather than your fasting window, as alcoholic drinks provide energy and therefore break a fast.9
Following national low-risk drinking guidelines is also recommended. In New Zealand, this means limiting intake to no more than 2 standard drinks on any day and including several alcohol-free days each week.10
If weight management is your goal, choosing lower-calorie options and avoiding sugary mixers may help reduce overall calorie intake.
Summary
If you choose to drink alcohol while practising intermittent fasting, consume it during your eating window, follow low-risk drinking guidelines and be mindful of the calories alcoholic drinks contribute.
