There's a lot of information out there, and not all of it agrees with each other. You might see one article or study that says coconut oil is bad for you while there's another that says you should eat it with every meal. Likewise, your doctor might tell you that eating red meat will increase your risk of heart disease, but your nutritionist says that there's nothing wrong with red meat. In recent years, news has come out that may have contradicted the wisdom from your doctor for the past 20 years.
So how do you figure out what to believe? What's actually true?
First we need to figure out why all of this conflicting information is happening. For one thing, the study of nutrition is relatively young. Doctors historically focus on preventing and curing diseases rather than focusing on creating health in the average person. This can lead to a lack of information for someone trying to avoid those things. The medical industry is one that surrounds disease, not health. In addition to this, doctors aren't always trained to help with your nutrition. This isn't their fault - they just don't receive extensive nutrition training in medical school. Their recommendations are based around popular understanding and what health agencies are saying is true - and sometimes the health agencies get it wrong, like in the case of saturated fat.
Secondly, there are a lot of studies out there. We would like to think that all studies are conducted with integrity, but this is aways the case as we found out when the sugar industry paid off researchers to downplay the hazards of sugar and instead blame fat for popular disease concerns. It's not cheap to conduct high-level research, and scientists are often funded by interested parties. This isn't to say that they are completely lying about the results, but they are able to design studies to produce the results they want.
Studies are looking for answers, but ultimately they can only provide us correlation. Correlation means that there may be a connection between two variables. For instance, if I eat red meat it may lead to heart disease. But this is not the same as causation, which is something that no study is able to prove as fast. No study can say that red meat causes heart disease. There are two many factors and variables to make such a claim.
Let's say there is a perfect, integrity based study. It should give us accurate results no matter what, right? Well.. measurement tools can be tricky as well. If you're counting calories based on labels, they can be off by up to 50%. We all absorb different amounts of food. So, for example, just because we both eat an apple, doesn't mean you are absorbing as much sugar from the apple as I am. In the same framework, if we both run one mile, our calorie burn difference can be anywhere between 3-45% different. If all of this wasn't enough, the diets and exercise you have done in the past can effect how you body reacts to a diet and exercise now.
If you think researching nutrition is tough, reporting on it is even harder. Journalism is based around sensationalizing the news - you know this, think about all the bad stuff you see on TV on a regular basis. In journalism school, they teach you, "If it bleeds, it leads." The same goes for nutrition news. What's going to get your attention more? A study that says "Only those with specific health parameters react poorly to eating red meat" OR "Red meat is killing you." Journalists can, unfortunately, over-emphasize things to make them interesting, flat out misunderstand a study, or don't look at the bigger picture and purpose of a single study. It's not their fault, they're trying to help but it's important to read multiple sources from multiple perspectives to get a better idea of what is really true.
Lastly, your nutrition is personalized to you. There is no cookie-cutter, one-size-fits-all method that will work for everyone. What worked for your best friend, might not work for you. This is because you have unique genetics that make you body react differently to different foods. In addition to this, there are a wide range of variables that can effect how you body processes food - how much you sleep, how much water you drink, what type of food you eat, how stressed you are, how much you exercise, any allergies you have, etc.
Maybe eating red meat doesn't actually work for you. Maybe eating broccoli hurts your stomach. There are a lot of different factors that make up your perfect nutrition. Read everything with a grain of salt, ask for help when you need it, and don't feel like you have to do whatever diet plan is popular right now (because there's a chance it won't be around in 5 years).