With so much readily available information on nutrition, I'm going to help you filter the good from the bad to make sure you don't fall into the common pitfalls. Remember to always use common sense when taking advice from the internet and research any facts presented to you. As the saying goes, if something sounds too good to be true, it usually is.
Changing too many things at once
Often times when trying a new diet, people will go all in. They'll be really good at sticking to it for a week, or two at best, before plummeting right back into their old habits. This is what happens when we try to change too much at once. Baby steps and keep it sustainable. Change one thing at a time, week by week. And make sure you are able to replicate these small changes each week before introducing a new habit. Before you know it, you will be eating well balanced meals with nutritious snacks in between without even craving junk food.
There are two reasons why I am not a fan of cheat days. #1 You are more likely to not only blow your calories out of the water for that day, but there will likely be a follow on craving that turns cheat day, into cheat week, cheat month and wow that year went fast. #2 You are overworking your will power. Just like any muscle, if you over use your will power, it will collapse and you might find yourself on the couch in an ice-cream coma.
So how can I indulge in the things I know aren't that great for me? I prefer cheat meals. This way, sure, you might still go over your calories for the day, but no where near as much if you were to binge the whole day. You will also to keep your cravings at bay and your will power intact, making it a lot easier to walk straight past the cafe with those awesome pastries.
Over eating 'healthy' foods
I see this way to often. Before you eat anything, always check the nutritional information. Just because something is for example, gluten free, vegan, sugar free or paleo does not mean that it is good for you or going to help you lose weight. Natural sugar is still sugar. Many of the protein balls, paleo or vegan slices you will come across are extremely calorie dense. At the end of the day, weight loss is still about calories in versus calories out and being in a calorie deficit. Which brings me to the final nutrition weight loss mistake
Portion size and balance
Say you are eating lean meats with whole grains and tonnes of veggies. If you still eat more than your body needs, you will gain weight. However, this is usually not a problem. The problem occurs when people say they are having healthy meals, but the balance is all wrong. Let's use rice with meat and vegetables as an example. That sounds great on the surface, until you look at the ratio of the food groups. This meal is usually served as majority rice, then meat, then vegetables. So we end up overeating on carbs and not getting enough protein, fibre and nutrients. So perhaps, we need to adjust the ratio by increasing the vegetables, reducing the rice and swap fatty meats for lean meats.
If all else fails, just remember; Eat food, mostly plants, not too much.