The link between coffee consumption and reduce risks for diabetes and heart disease is confirmed.  

Coffee is one of the most popular beverages consumed in the United States and worldwide.  Depending on the method used to measure, it is recorded as being number one or number two if you exclude water as a beverage.  Amazingly, the US is number nine with 115 liters per person​[1]​.  In my years as a physician, I have read many journal articles and news reports that coffee is bad for your health.  It now appears that the evidence is going that this is not the case.  

A new study from November 2017 adds to the prior evidence and appears to confirm the benefits of coffee.  The study, “Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes”, is a meta-analysis of prior studies​[2]​.  The umbrella review identified 201 meta-analyses of observational research with 67 unique health outcomes and 17 meta-analyses of interventional research with nine unique outcomes.  The study found that coffee consumption was more often associated with more benefit than harm for a range of health outcomes. There was evidence of an association between coffee consumption, up to 4 cups a day, and a benefit for all-cause mortality cardiovascular mortality, and cardiovascular disease.  Also, higher consumption of coffee was associated with an 18% lower risk of incident cancer and a significantly lower risk to develop diabetes type 2.  

Not all are positive forms the study.  There was a high risk of harm with coffee consumption for low birth weight in pregnancy, preterm birth, and pregnancy loss. There was also an association between coffee drinking and a higher risk of fracture in women but not in men.

So why is this tied to weight loss and obesity?  This question is obvious is you think of the mechanism for diabetes type 2 and cardiovascular disease.  These two diseases are linked in most patients to metabolic syndrome.  If you lower the risk of heart disease and diabetes, it is probably by lowering the risk or degree of metabolic syndrome.  More research is needed to confirm, but I would give an educated guess that this is the mechanism.  

The bottom line: Coffee is a healthy drink to add to your diet, but I recommend keeping it to 4-5 cups a day and stopping before noon.  The benefits clearly outright this risk as long as you are not pregnant.  More research is needed to quantify the risk of fractures in females. You may find my prior articles on coffee of interest.  I wrote about the research that backs up the use of coffee for weight loss, lowering your mortality, and reducing your risk for metabolic syndrome.