A bit of alcohol won’t kill ya…

But it does promote hypoglycemia. In this state, over consumption of food is likely as the feedback mechanism is slow. Thus, by the time you have eaten enough to satisfy the symptoms of hypoglycemia (more than hunger), blood sugar levels are once again higher than they should be--promoting another surge in insulin and the roller coaster of blood sugar highs/lows continues. Neither high nor blood sugar are desirable from a health standpoint.

Additionally, a large number of studies over the last several years link alcohol consumption to insulin sensitivity. For example, a huge study from the Graduate School of Medical Science at Kyushu University clearly demonstrated that regular consumption of alcohol correlated with decreased insulin sensitivity.

If you are insulin resistant, you will tend to easily gain weight, particularly abdominal body fat when you take in processed carbs. You will also increase your risk for type 2 diabetes. As it concerns weight loss, insulin resistance definitely predisposes you towards weight gain (and a host of other adverse health effects). Several scientific periodicals, including the European Journal of Endocrinology, have conducted studies which show a clear connection to alcohol intake and ghrelin inhibition. Ghrelin is a key hormone involved in hunger signaling and satiation.
Also, acetate is the end product of alcohol, and the American Journal of Clinical Nutrition published a report in 2004 that made clear that the conversion of alcohol to acetate inhibits lipolysis, or fat burning.

Oh, yeah, and alcohol also suppresses the production of prostaglandins (hormone-like substances which modulate inflammation, stimulate tissue repair, etc) which directly contributes to leaky gut.

Lastly, regarding stress on organs of detoxification, the body is always having to eliminate toxins--both from inside and outside the body. When faced with artificial colors, flavorings, preservatives, pesticides, fungicides, pharmaceuticals, etc that the body is bombarded with everyday in the modern world, the occasional drink can be the straw that broke the camels back.