Indeed, a telling study by the New York Times last year revealed a huge discrepancy between science and public opinion when it comes to nutrition.
Granola was deemed healthy by 71 per cent of the public, but only 28 per cent of nutritionists agreed.
Nutritionist Tammy Lakatos Shames, of the Nutrition Twins, gives Daily Mail Online the scoop on 10 foods that are not so great for you - and what you could be having instead.
1. CEREAL
Cereals are often branded as being part of a healthy, balanced breakfast.
But in reality, many of the most popular brands are actually full of unhealthy ingredients.
"Unless you're choosing the whole grain option, cereal can cause a surge of blood sugar, which releases insulin and that being repeated every day is not good for your body," said Shames.
"The calories add up really quickly and you're hungry before you know it. You can have one portion of cereal and be adding 400 calories to your day."
2. FRUIT JUICE
Shames says you can still get a dose of antioxidants from drinking a glass of fruit juice but, unlike when you eat whole fruit, the calories are more concentrated.
"The brain doesn't compensate for the calories because they're so concentrated like with whole fruit and so your blood sugar levels skyrocket," she said.
Eating whole fruits and vegetables is preferred, with juicing primarily reserved for situations when daily intake of vegetables and fruits is inadequate.
And if you do juice, avoid adding extra sugar by putting in honey, to minimise calories.
3. SUSHI
Just as with the fruit juice, Shames says sushi can be great if you're choosing healthier options such as with lean protein and vegetables.
But some of the "fancier" types end up covered in sauces loaded with fats and sodium or refined white rice.
"Typically, it's hard to get a lot of fibre or to get vitamins and minerals out of sushi," she said.
"Plus you need to be careful with raw fish because you can get really sick."
4. GRANOLA
It can be a nice oatmeal topper, but most of granola options that you pick up at the grocery store are loaded with hydrogenated oils and added sugars.
A serving size of granola is actually a one-quarter cup, but most people are eating far more than that amount.
"If you're pouring a bowl, you can be eating upwards of 200 calories or more, and sometimes get your calories for the entire day," Shames said.
"So it's much better to stick to options that have whole grains and limited amounts of sugar."
5. FROZEN YOGURT
The treat is often seen as a healthier alternative to ice cream - and it can be a real hit or miss.
Many self-serve shops have frozen yogurt options that have high amounts of sugar and fat.
Shames even admits that it's her guilty pleasure and something she needs to be wary of.
"If you pick the low-fat, or fat-free option, you have a much less chance of eating something that's going to clog your arteries," she says.
And be wary when it comes to the toppings bar. If you fill your cup with candy and chocolates, it's almost as bad starting with a sugary flavour of frozen yogurt.
6. MEAL REPLACEMENT BARS
Shames says the problem with bars meant to replace a daily meal are the ingredients.
She said: "They're high in calories and don't fill you up that much.
"Many times, you're no better off than if you ate a candy bar."
And the nutritionist says that many of her clients have eaten the bars for years and up developing toxicity symptoms.
"Many of these bars are high in hydrogenated oils, which load up on cholesterol. I've even had clients that have their hair falling out from it."
7. SMOOTHIES
Smoothies can be a healthy option if you make them yourself, Shames says.
But many of the drinks that you get at juice bars and restaurants are rather unhealthy.
"They're high in calories, they blend in a lot of fruit which concentrates the calories and then add in sugar," she said.
"Pretty soon you have a drink in front of you that's 700 or 800 calories."
Shames recommends making a smoothie at home, adding Greek yogurt for protein, and frozen fruit for both flavour and texture.
She added: "This way you know what you're getting and you don't even need to add sugar because they're sweet to begin with."
8. COCONUT OIL
Coconut oil has been part of a huge craze, but it's actually only beneficial in small quantities.
"If you look at the research, it show that the fatty acids can clog your arteries and really place a lot of pressure on the heart," Shames said.
To save on calories, she recommends putting the oil in a spray bottle when you're coating a pan for cooking.
And if you're looking for a replacement, she says better alternatives include avocado oil or olive oil.
9. TRAIL MIX
Just as with the smoothies, Shames says trail mix can be a healthy snack if you make it yourself.
"The trail mix you buy at the store often has a lot of items that add up the calories really quickly," she said.
"And many options have dried fruits that are full of sulphites, food preservatives which we know to be carcinogenic."
To make a healthy version, she says to have pre-portioned containers ready and measure by adding some unsalted nuts, a bit of dark chocolate or candy M&Ms, and sulphite-free dried fruit.
10. MARGARINE
In the 1960s, when the US was waging its war on fat, margarine took off in popularity over butter.
But many margarines are actually unhealthy due to their hydrogenated oils.
"They're full of trans fats, which we know is bad for cholesterol and for the heart," Shames said.
"At the end of the day, a tablespoon of butter is better for you than a tablespoon of margarine."
But if you're very concerned about both options, Shames says you can buy a brand like Smart Balance which is low in fat and oils.
