What should humans eat in order to be healthy and live a long, disease free life? This nagging question has fueled thousands of scientific studies on diet, genetics, and human biology. But as more studies have been done, the answer to this question seems to get fuzzier, not clearer.

New diets preaching the "ideal" way to eat for health are continually springing up. They all claim to be the path to a disease-free life. They also promise you'll lose those last couple of pounds you've been dying to get rid of. Weight loss is the marketing pitch most fad diets rely on, but actual results can vary drastically.

"Vegan. Paleo. Keto. Raw foods only. The Mediterranean Diet. The Carnivore diet."

You can find studies, real results, and rave reviews from participants on every diet. There are entire reddit boards dedicated to each diet, with as many success stories as horror stories. How can someone lose almost 30 lbs in 90 days on "the carnivore diet" with no vitamin or mineral deficiencies to speak of, while someone else could lose 78 lbs in 13 months and no longer be considered diabetic after going completely vegan?

The ideologies of the two different diets are worlds apart. One is strictly plant-based, with no animal products allowed. The other advises you to eat only animals, with no vegetables, fruits, grains, legumes, nuts, seeds, or starches permitted. The sliver of truth here seems to be that different diets work for different people. There isn't a one-diet-cures-all rule for the entire human population. Although, if you spend enough time really digging deep into the reputable research, there are few basic rules you can follow for good health.

Followers of both veganism and the carnivore diet can agree on one popular Michael Pollan rule for living: choose food over food-like substances. Food used to be the only thing you could really eat—real, unprocessed whole foods. But in the age of industrialized farming and manufactured shelf lives, you can find entire grocery aisles filled with things to eat that don't qualify as "real food."

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What counts as real food?

According to Pollan, you shouldn't be eating anything your great grandmother wouldn't eat. He advises you to put the Go-Gurt down and anything else with ingredients you can't pronounce. A healthy rule for eating is to focus on whole foods and avoid packaged foods with more than 5 ingredients.

Shop the perimeters of the grocery store aisles where you'll find real fruits, vegetables, meats, eggs, and dairy products. Avoid the middle aisles full of packaged, processed foods. Research has shown that ultra-processed foods are linked to the development of cancer. They're also lacking in nutritional value.

What about meat?

Despite the popularity (and numerous success stories) of the ketogenic diet, many studies are warning followers of the long term effects. To many, short term results seem to show drastic weight loss and surprising health benefits. The Netflix documentary, The Magic Pill, claims the keto diet can heal anything and everything and reduce dependency on prescription drugs in as little as 5 weeks. Diabetics following this high-fat, protein diet even claim they no longer need their insulin, which has doctors warning patients to focus on the long term effects and not just the short term gains.

Restrictive diets like keto and mono-diets like the carnivore diet may deliver fast weight loss and the temporary health benefits that come with it, but they're difficult to maintain. Many doctors and researchers are noting that followers of keto have usually had unhealthy diets high in processed foods and sugar before switching over. The quick health benefits they experience are likely from cutting out said sugar and consuming more whole foods than from the diet itself.

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In fact, reputable studies have shown that eating a moderate amount of carbs (about 50-55% of your calorie intake), instead of a low carb diet, actually increases longevity. A Harvard study also found that diets that replace carbs with fats and proteins from meat and dairy products increase the risk of heart disease and cancer. The best thing you can do for your health is to eat a variety of whole foods.

Eat mostly plants

The National Institute for Health reports that a vegetarian diet is beneficial in the prevention and treatment of numerous diseases and that vegetarians are more likely to live longer lives. This is due to the fact that including a wide variety of fruits, vegetables, nuts, seeds, and grains in your diet will provide a higher intake of vitamins and minerals.

But do you have to give up meat entirely? No. Going plant-based doesn't mean you have to give up meat entirely. A plant-based diet allows for moderate amounts of lean meats, poultry and fish. The Institute of Medicine and a Harvard Study actually recommend eating a few servings of fish per week to reduce the risk of having a heart attack by as much as 30%!

Michael Pollan's advice to "eat food, mostly plants, not too much" means that it's best to focus on plant-based foods, but his research didn't conclude that eating meat was bad for you. There isn't conclusive evidence that meat is harmful for your health, as long you eat quality meats in moderation and include plenty of plant-based foods in your diet. When you do eat meat, make sure you reach for un-processed, antibiotic free, grass fed cuts.

If you're looking for quality animal protein, here are the best places to order healthy beef, poultry, and seafood online:

Poultry: Murray's Chicken

Murray's family owned farm raises their chickens in the rolling hills of southern Pennsylvania. Chickens are certified human and vegetarian fed for the best health and taste. Poultry is free of antibiotics, growth drugs, and hormones. You can order Murray's Chicken here or check out where they're poultry is available for sale in stores.

Beef, Lamb, Bison, Pork, Seafood: Grassland Beef

Grassland Beef is a great resource if your looking for 100% grass fed and sustainably raised beef, bison, lamb, and pork. You can even order healthy, wild caught seafood. Cattle grazes on the US Wellness meats farms. Their beef is healthier for you because you're getting all the added nutrients that come from cows feeding on real grass and not grain. All meat is free of pesticides, hormones, and antibiotics. You can place your order here.