At long last, summer has arrived. Whether you prepared for the impending spike in shirtlessness by embarking on a months-long diet-and-exercise program or found yourself scrambling for a last-minute alternative a week before Memorial Day, it's doubly important that you keep making smart choices so all that hard work—you did work hard, right?—doesn't go to waste. And since nutrition scientists seem to be constantly declaring that new foods are good or (usually) bad for you, we asked Steve Hertzler, Ph.D., R.D., of EAS Sports Nutrition to fill us in on what the latest research says—and to help us brush up on some of the basics, too.

You probably need more protein than you're eating. I know you're very diligent about your chicken-breast consumption, but still. Recent studies show that Americans may need anywhere from 50 to 175 percent more protein than suggested in the Recommended Daily Allowances promulgated by the federal government. An active adult male who weighs 154 pounds should aim to consume anywhere between 119 and 154 grams of protein per day, but the RDA guidelines suggest that you take in a measly 56. If you're working out and lifting weights, your body needs that fuel to repair itself and build muscle. Don't skimp.

Eat more seafood. Burgers are great, but maybe try throwing some salmon on the grill at your next cookout, too. Omega-3 fatty acids found in many fish are critical to reducing the types of inflammation that have been linked to obesity, dementia, diabetes, and heart disease. A Harvard Medical School study found that eating one or two small servings of fish per week reduces the risk of death from heart disease by a whopping 36 percent.

Eat fewer refined carbs. For a bunch of reasons: Choosing more fiber-rich foods and whole grains will help you manage weight, improve gut health, and reduce the risk of Type 2 diabetes. Diets that are high in fat and refined carbohydrates can cause imbalances in the good and bad bacteria in the gut, which in turn can cause gastrointestinal distress, wreak havoc on metabolism, and increase the risk of colon cancer. Stick with the good stuff: fruits, vegetables, and whole grains like whole-wheat bread and quinoa. (Maybe go bunless on that burger this weekend.)

Get more vitamins C and E. The bad news is that heart disease is the leading cause of death for both men and women. The good news is that, genetics aside, there are still things you can do to control the risk. Chronic inflammation is one of the primary factors in the development of heart disease, and it's heavily influenced by our eating habits. Vitamins C and E—two potent antioxidants—can help lower inflammation to reduce the wear and tear on your all-important coronary arteries. Things like walnuts, oranges, grapes, and leafy greens can help out.

Check your vitamin D levels. Researchers think that many Americans are deficient in their intake of the ol' sunshine vitamin, which is important for supporting muscle and bone health. Try eating more fortified milk, fatty fish, and egg yolks, but also, go outside! It's beautiful today.

Watch now:Inside Tom Brady’s Routine: What It Takes to Be the G.O.A.T.Jay Willis is a staff writer at GQ covering news, law, and politics. Previously, he was an associate at law firms in Washington, D.C. and Seattle, where his practice focused on consumer financial services and environmental cleanup litigation. He studied social welfare at Berkeley and graduated from Harvard Law School... Read moreRelated Stories for GQHealthHealth