How to use evidence to say what you want!
Conclusion:
When a headline sounds too good to be true, it usually is. There's nothing in this study to suggest that people should start drinking red wine to lose weight.
The potential effect of diet on the micro-organisms in the gut is a new and interesting field of science.
This study provides new evidence about a possible effect of substances found in red wine on the growth of micro-organisms in the gut, and suggests that this may affect the way the body works.
But the study has several limitations. Because it's cross-sectional, it shows us only a snapshot in time.
We do not know how the women's gut micro-organisms, BMI or red wine consumption changed over time.
This means we cannot say whether 1 of these factors may have been directly influencing the other.
Because it was an observational study, we do not know whether red wine was the cause of differences in BMI or gut micro-organisms.
Other factors may have been involved, such as women's overall lifestyles.
The researchers did try to adjust for the impact of some factors, but it's difficult to remove them completely.
Also, the study relied on women's reports of how much alcohol they drank. People often underestimate how much alcohol they drink.
We know there's a big downside to drinking alcohol, especially in excess. There's no "safe" level of alcohol consumption, but drinking less than 14 units of alcohol a week is considered low risk.
Regularly drinking more than this increases the risk of several types of cancer, stroke, heart disease, liver disease, brain damage and nervous system problems.
For people who enjoy an occasional glass of red wine and drink less than 14 units a week, this study suggests they may have more diverse gut flora.
But there's no reason to start drinking red wine in the hope of achieving improved gut health or losing weight. The study does not provide enough evidence of this
