Neither milk, nor calcium increases the metabolism

Background

One thing that you'll hear often in response, when people report that dairy caused acne, that "milk/calcium increases the metabolism and hence the need for nutrients such as vitamin A" (i.e. here). This motivates people to supplement with high amounts of vitamin A to antagonize the acne-forming properties of milk.

"The milk estrogen research isn't good. It also contains thyroid and progesterone and other protective substances. The high calcium content helps to increase the metabolic rate, and probably contributes to maintaining the anabolic balance." - Ray Peat

"Regarding milk and its tryptophan content, The calcium helps to keep the metabolic rate high, and the other nutrients help to steer tryptophan away from the serotonin path." - Ray Peat (E-Mail exchange)

Review

I looked up studies on that subject and there are quite a few published. All I have found indicate that neither milk nor calcium increases one's metabolism. There are some other interesting findings.

• In a 1-week trial with healthy participants (mostly male), an energy-balanced high-calcium diet did not increase the metabolic rate compared to a low-calcium diet. However, under energy deficient conditions, the high calcium diet lead to a higher fat oxidation. http://www.ncbi.nlm.nih.gov/pubmed/16421344
• In a 1-week trial with healthy normal-weight men, neither a high calcium carbonate or a high dairy calcium diet increased the metabolic rate. A non-significantly increased fat oxidation was found. http://www.ncbi.nlm.nih.gov/pubmed/16332657
• In a 3-week controlled trial with overweight children neither calcium carbonate nor milk products increased total energy expenditure. http://www.ncbi.nlm.nih.gov/pubmed/21918216
• In a 5-week controlled trial with overweight low-calcium consumers, an 800mg dairy calcium supplementation did not increase resting energy expenditure. However, a non-significant trend towards less carbohydrate oxidation and more fat oxidation was found http://www.ncbi.nlm.nih.gov/pubmed/18842771
• A 12-week RCT with overweight women, comparing control vs. 900mg calcium-carbonate vs. high dairy found no increase in total energy expenditure in either intervention group. In the calcium supplement group an increase in fat oxidation was found. http://www.ncbi.nlm.nih.gov/pubmed/18421269
• In a 9 month RCT with obese subjects, a recommended dairy diet did not lead to an increased resting metabolic rate compared to a reduced dairy diet. http://www.ncbi.nlm.nih.gov/pubmed/18950508
• In a 1-year controlled trial with healthy women, a chronic high-calcium intake increases fat oxidation to both low and high calcium meals compared to a chronic low-calcium intake. An increase in PTH during the trial correlated with a lower fat oxidation and vice versa. http://www.ncbi.nlm.nih.gov/pubmed/16332655
• In a meta-analysis of trials, both chronic and acute calcium intake was found to increase fat oxidation http://www.ncbi.nlm.nih.gov/pubmed/22708505
• In a randomized trial of adolescent girls with low dairy intake, girls randomized to increase their calcium intake did not loose more weight than girls on the continued low-calcium diet http://www.ncbi.nlm.nih.gov/pubmed/28298396
• In a 24-week trial with obese subjects on an energy-deficit diet, people randomized to 800mg calcium carbonate/day or a high-dairy intake lost more weight than people on an average calcium intake. Dairy intake lead to greater weight loss than supplemental calcium intake. http://www.ncbi.nlm.nih.gov/pubmed/15090625
  Similar results have been found in a similar trial under energy-deficit conditions. http://www.ncbi.nlm.nih.gov/pubmed/21775530
• In a 1-week trial of healthy moderately overweight people (mostly female), a 1800mg calcium diet did not increase 24-hour energy expenditure compared to a 500mg calcium diet. A non-significantly increased fat oxidation and a decreased carbohydrate oxidation was found. However in the group with a high-calcium and normal-protein intake (%15 E of protein), a higher fecal fat and energy excretion was found. In the discussion, the authors said that calcium can form complexes with fat that hinder them from being absorbed, but on a high-protein diet, the calcium binds to the protein and not the fat, leading to a reduction in the fat excreting effect of calcium. http://www.ncbi.nlm.nih.gov/pubmed/15672116
  These results have also been found in a meta-analysis of calcium trials. http://www.ncbi.nlm.nih.gov/pubmed/19493303
  And in line with that study another study found that a high calcium meal reduces the lipid content in the blood compared to a low calcium meal, presumably by reducing fat absorption http://www.ncbi.nlm.nih.gov/pubmed/17344487
• In an observational study, high acute calcium intake was correlated with higher fat oxidation, which correlated with a lower respiratory quotient. Dairy intake was not a more important predictor of fat oxidation than total calcium intake. http://www.ncbi.nlm.nih.gov/pubmed/12586999

Conclusions 

• Milk or calcium does not increase the metabolic rate according to the published evidence. The beneficial effects of dairy consumption on body weight appear to be partly mediated by a shift away from carbohydrate towards fat oxidation and a higher fecal excretion of fat. Milk products only favor weight loss in the context of a calorie-reduced diet, but in that context they are superior to low-calcium non-dairy diets.
• In that sense, the acne-increasing properties of milk seem to be unrelated to a general metabolism increasing effect. Possibly, other mechanisms appear to be at play such as hormonal effects, gut irritation of the hard to digest casein/whey proteins or allergic/histamine/inflammatory reactions. The beneficial effect of vitamin A on acne may be unrelated to the metabolic rate and simply be a consequence of its anti-keratinization properties, leading to less clogging of sebum within the pores.