You may just be losing fat and gaining muscle, which is a trend in the right direction, but one that won't show on the scale. And, yes, drinking alcohol can put the brakes on a weight loss program in more ways than one. In the first place, you've got to consider the excess calories you're taking in. There are seven calories per gram of alcohol. A single glass of white wine or an ounce and half of hard liquor provides about 90 calories; a regular beer gives you 150 (a light beer provides about 110). You can almost double the calories in hard liquor if you add a mixer such as fruit juice or tonic water. A typical martini contains 210 calories and a Pina Colada in excess of 300. When you're trying to lose weight, alcohol also works against you because the calories it supplies are "empty" - they provide you with no beneficial nutrients.
Another consideration: alcohol can also slow the process by which your body burns fat. The alcohol calories you consume aren't stored. Instead, they're converted to acetate, a type of fuel that the body burns quickly. As a result, you burn off your alcohol calories before you burn the fat you are trying to eliminate by increasing your exercise and cutting back on your food intake.
Also, alcohol can actually stimulate your appetite, loosen your inhibitions and undermine your willpower, causing you to eat more than you planned. A 2002 Danish study published in the International Journal of Obesity and Related Metabolic Disorders found that men who were told they could eat as much as they wanted ate more when meals were served with beer or wine rather than soft drinks.
You can work an alcoholic drink into your weight loss program, but to do so, you'll have to account for the calories. For example, if you're on a 1,500 calorie per day diet, you can have a glass of wine with dinner - but only if you make sure that your food calories total no more than about 1,400. By the way, you shouldn't need alcohol almost every day. I would recommend a trial of no alcohol or only 1-2 drinks weekly for a period of 4-6 weeks to see if it helps with weight loss. If not, you may have to re-evaluate your program, perhaps by consulting a bariatrician (weight-management doctor). And if you are drinking alcohol as frequently as you say, I also recommend that you take milk thistle daily to help protect your liver.
Andrew Weil, M.D.