Fresh is best. Eat a rainbow. If possible, cook from scratch.
These are three of the golden rules of healthy eating, repeatedly touted by nutritionists and food scientists.
But now a growing number of nutritionists say this advice is outdated.
Many of the country's largest food stores, they say, now offer frozen TV dinners that are just as nutritious as if you were eating them fresh.
“I grew up with a mom who made microwaveable frozen meals, and they were extremely high in sodium, fat and preservatives,” Sarah Garone, an Arizona nutritionist, told DailyMail.com. “But we've come a long way since then.”
Nutritionist Sarah Garone has told DailyMail.com that frozen TV dinners have come a long way from the bland meals of the 1980s that were stripped of nutrients
She even said that some foods are actually healthier when frozen, giving the example of frozen fruits and vegetables.
'Fruits and vegetables often contain more nutrients if you buy them frozen because they are harvested at the peak of their freshness and then immediately preserved, which preserves their nutrients.'
Contrary to what some think, she adds that freezing meat and dairy makes no difference to the amount of essential substances they contain.
Trader Joe's is a supermarket that is a leader in healthy frozen meals. Here, Sarah Garone gives her expert opinion on the best options you should all buy.
Cauliflower gnocchi
*all nutritional information is per serving
Calories: 140
Salt: 460 mg
Sugar: less than 1 g
Saturated fat: 0.5 g
Price: $3.29
These low-calorie Italian dumplings are made with just five ingredients: cauliflower, cassava flour, potato starch, extra virgin olive oil, and sea salt.
The lack of wheat, sugar, dairy or eggs translates into significantly less fat and calories than purely potato-based gnocchi varieties.
Ms Garone said: “I would put something on it, but as it is, it's pretty good. It only has five ingredients, which is great.'
This means there are fewer additives than you might get in other products, such as artificial sweeteners that have been linked to weight gain.
“I think most people want to at least add a sauce, maybe some ground tofu or ground turkey, something like that to make it more of a meal,” Ms. Garone adds.
'It contains six grams of fiber (the same as in three slices of whole wheat bread) and only half a gram of saturated fat, which is the harmful type.'
A top nutritionist has given her thoughts on the five healthiest frozen meals Trader Joe's offers, including some you wouldn't think are nutritious, like fried rice and burgers
Fibers are important because they keep you feeling full for longer and are less likely to snack.
Diets high in nutrients have been linked to a lower risk of diabetes, heart disease and some types of cancer.
'Cauliflower will have more potassium, calcium and fiber than regular versions of gnocchi. It's a nice way to use some vegetables where you wouldn't otherwise get them.'
“Since most of us don't get enough vegetables, it's nice to have that built in, especially with ready-made meals like a frozen meal,” she added.
Quinoa Cowboy Veggie Burgers
Calories: 180
Salt: 310 mg
Sugar: less than 1 g
Saturated fat: 1 g
Price: $3.99 for 4
Next up is a low-fat, low-calorie veggie burger with virtually no sugar or fat.
Nutritionist Sarah Garone said: 'Quinoa is a good choice because as well as protein (about as much as in one egg) it also contains fibre, which helps you feel full.'
Ms Garone added: 'Adding a whole wheat bun would be a good choice. It would add extra calories, which is necessary because this is too low for an entire meal.
“That would also add more fiber and more B vitamins.” You can also add a slice of cheese to increase the protein.
And unlike other frozen burgers, these are low in sodium: just over 10 percent of the recommended amount in one burger.
Premium Salmon Burgers
Calories: 100
Salt: 330 mg
Sugar: 1 g
Saturated fat: 0.5 g
Price: $7.49 for 4
These super low-calorie salmon burgers are a great option for people looking to lose weight.
They're made from Alaskan salmon, and little else, and contain 15 grams of protein — a third of the amount Americans should have daily, according to U.S. health officials.
This keeps you relatively full, without the extra sugars and fats in other burgers.
Ms Garone said the calorie count is “quite low”, which can be useful for people on a controlled diet, but they may need to supplement with a whole wheat burger bun, sauce and vegetables.
She added: 'What I also like about these is that they provide 100 per cent of your daily vitamin D – which is crucial for bone health, among other things.
'This time of year most of us aren't spending time in the sun, so we may not be getting our share of vitamin D and eating can help you reach your daily target.'
The total lack of fiber is a downfall, but pairing it with a whole-wheat bun, sweet potatoes and other vegetables will solve that problem, she says.
Vegetable fried rice
Calories: 230
Salt: 510 mg
Sugar: 3 g
Saturated fat: 0 g
Price: $2.99
This popular Asian dish is a rare sight in the frozen food aisle – and Ms Garone said it deserves a spot in the roundup of the healthiest meals.
She said, “I know you don't consider fried rice healthy.
“But in this case, the fat is low, and while the sodium is high, it's not astronomical: 22 percent of the recommended daily allowance.”
Most importantly, it's packed with vegetables, providing a wide range of 'hidden' essential micronutrients, which is especially useful for children who avoid vegetables.
“I buy this and my kids eat it,” Ms. Garone said. 'It contains carrots, edamame, corn, peas, leeks, peppers. Trader Joe's has it pictured with a fried egg, which I think is a good addition for some protein, or you can always add some grilled chicken strips.”
But be careful with portion sizes.
Ms Garone added: 'If you want to stick to the nutritional levels you see on the label, measure that against the cup. The serving size is one and a half cups and that's only 230 calories. '
In addition, the dish contains no saturated fat. “This is surprising because you think fried rice will be very oily and greasy, but it isn't,” she said.
Grilled Chicken Strips
Calories: 110
Salt: 230 mg
Sugar: 0g
Saturated fat: 0.5 g
Price: $8.99
These are “super versatile for busy people who want a protein boost,” Ms. Garone said.
'They are high in protein, 20 grams per serving, and low in fat and sodium.'
About five strips provide almost half the recommended daily amount of protein, which helps you stay full and is crucial for muscle growth.
'It's something you can top a salad with, throw into pasta or put in a burrito. There are endless possibilities, which is nice,” she added.
'Eating healthy is a matter of setting yourself up for success. You don't have to have the whole plan ready as long as you have the building blocks and I think this would count as a building block for healthy eating. So it gets my vote.”