Ever notice your jeans feel tighter after a night out or that your workouts don’t seem to cancel out your drinking? Alcohol can play a surprisingly big role in weight gain, especially for women. It’s not just the calories — alcohol changes how your body burns fuel, affects hormones, and influences behavior.
A single glass of wine is about 125 calories, a pint of beer around 200, and many cocktails can top 300 calories because of sugary mixers. These are mostly “empty” calories — little to no nutrition. To put it in perspective: a small apple is about 80 calories and a chocolate chip cookie about 150. One extra drink can be like adding a snack, and multiple drinks add up fast. Bars and restaurants often pour larger servings than a standard 5-ounce glass of wine, and liqueurs or after-dinner drinks can be shockingly calorie-dense (for example, 1.5 ounces of Baileys is roughly 147 calories).
When you drink, your body prioritizes breaking down alcohol over other processes. The liver enzyme alcohol dehydrogenase starts converting alcohol into acetaldehyde, which is then converted to acetate and eventually expelled as carbon dioxide and water. While this is happening, fat burning slows down. Alcohol also supplies seven calories per gram — nearly as dense as fat — so those calories add up while your body delays using stored fat.
Alcohol also affects appetite and decision-making. It can raise hunger, lower inhibitions, and make high-calorie foods more tempting. Drinking on an empty stomach amplifies these effects, making bar snacks and late-night takeout harder to resist.
Hormones are another piece of the puzzle. Alcohol can raise estrogen levels, which influences where the body stores fat, and can affect cortisol, the stress hormone, which increases cravings for sugary, calorie-rich foods. It can disrupt insulin regulation, raising the risk of insulin resistance and higher blood sugar. Alcohol also harms sleep quality — even if it helps you fall asleep, it disrupts deep sleep — which changes levels of ghrelin and leptin, the hormones that control hunger and fullness, and can lead to overeating.
Social situations make it easy to drink more than you plan. Happy hours, parties, and celebrations encourage extra drinks, and cocktails with sugary mixers or craft beers can be much higher in calories than you expect.
Aging changes how alcohol affects you. Loss of muscle and a slower metabolism mean you burn fewer calories at rest, and alcohol can further reduce muscle protein synthesis. Older adults have less body water, so alcohol is less diluted and can lead to higher blood alcohol concentrations. Menopause-related hormone shifts can increase abdominal fat in women, and alcohol can worsen those effects. Chronic drinking also harms bone health by interfering with calcium and vitamin D balance, raises the risk of sleep problems, and can interact badly with medications or existing health conditions.
Knowing how alcohol influences calories, metabolism, hormones, and behavior can help you make smarter choices. You don’t have to give up drinking entirely, but being mindful about how much and what you’re drinking — choosing lighter options, watching portion sizes, and avoiding sugary mixers — can make a real difference. If you want a structured reset, eliminating alcohol for a short period, like three weeks, can help jump-start weight loss and improve metabolic health.
