These unhealthy eating patterns don’t just trigger weight gain and undermine your energy. They age you from the inside out.

If the only edible indiscretions you worry about are those that make you gain weight, you may have your priorities mixed up. The worst dietary demons — including many sugary, fatty, refined, and highly processed foods — do more than add unwanted pounds. They subtract years from your life.

Nutrition, not age, determines the body’s internal chemistry, which in turn affects the quality and resilience of virtually every organ, cell, and system in the body.

“Aging is not the passive process we once thought,” says Henry S. Lodge, MD, coauthor of Younger Next Year. “How gracefully you age is reflected by the food you eat.”

The condition of your skin and the quality of your bones, brain, and connective tissue are all influenced by diet. Your eating habits, therefore, play a big role in determining how quickly you see and feel the effects of aging.

The human body is a perpetual construction zone, replacing most of its cells every few months. The secret to aging well is to give your body the best tools for the job: whole, healthy food.

Of course, no one makes perfect choices all the time. But if weekly transgressions morph into daily habits, your body’s repair system will be undermined, says Lodge. “Bad food habits are like calling in the demolition team every day, but never calling the construction crew.”

Here’s how to identify and fix some age-accelerating food habits.

Body-Aging Habit No. 1: A Weakness for Convenience Foods

Big Offender: Partially hydrogenated oils (a source of trans fats), which manufacturers manipulate to increase stability and shelf life.

How It Ages You: Lurking in many processed convenience foods, partially hydrogenated oils take their aging toll by promoting inflammation. Chronic inflammation is a low-grade, systemic irritation that smolders deep inside the body. Like rust that spreads through a car, inflammation erodes the body’s basic mechanics.

Specifically, chronic inflammation ages the body by nibbling away at telomeres — the caps on the ends of your chromosomes that are key to protecting your genes. Telomeres shorten naturally with each cell division, and eventually telomeres are used up and cells become inactive or die. Cell death is natural, but lifestyle factors — such as eating a lot of hydrogenated oils — can shorten telomeres prematurely and accelerate aging. (For more on telomeres, see “The Big Picture: 5 Fundamentals of Lifetime Health“.)

“Inflammation is the No. 1 enemy of telomeres,” says Shawn Talbott, PhD, CNS, a nutritional biochemist and author of The Secret of Vigor. He explains that prematurely shortened telomeres are linked to heart disease, type 2 diabetes, and certain cancers.

Partially hydrogenated oils are full of trans fat. Although the U.S. Food and Drug Administration has recently made moves to ban its use in human food products, a legal loophole allows small amounts of trans fats to go into processed foods while still permitting those foods to be labeled as trans-fat-free.

A new report by the consumer-advocate Environmental Working Group noted that while “trans fat” appears on only 2 percent of Nutrition Facts labels, the fat is used in an estimated 37 percent of all supermarket foods.

“People think the war on trans fat has been won, but sleeper cells were left behind,” says Lodge. “Remember, food labeling is not completely honest.”

Bottom line: If your go-to meals are processed or if you snack on packaged cookies or crackers without paying close attention to serving size, you may be ingesting several grams of trans fats each day.

The Fix

Eat fewer processed foods. Shop the perimeter of grocery stores, where produce and fresh foods are displayed.

Eat more high-quality fats and get the omega-3 fatty acids found in salmon, halibut, anchovies, grouper, flaxseeds, chia seeds, and sesame seeds. These fats boost brain and nervous-system health by nourishing cell membranes, says Kathie Madonna Swift, MS, RDN, LDN, cofounder of the Integrative and Functional Nutrition Academy and coauthor of The Swift Diet.

A diet high in phytonutrients and antioxidants is also linked to longer telomeres, so eat plenty of leafy greens, berries, cruciferous veggies, and other brightly colored produce, and drink lots of green tea. (For tips on brewing, see “Learn This Skill: How to Brew Green Tea“.)

Body-Aging Habit No. 2: Giving In To A Serious Sweet Tooth

Big Offender: Sugar, whether sucrose (the refined, highly processed and crystalized version of plant sugars), glucose, dextrose, fructose, or other types of added sweeteners.

How It Ages You: Excess sugar in your diet loiters in the blood and causes trouble by glomming on to protein molecules. This process, called glycation, causes cellular aging in several ways.

First, it slows the body’s repair mechanism. Although glycation’s effects are mostly internal, aging skin is a prime external sign. “Sugar molecules gum up the collagen in your skin,” says Talbott, making skin less elastic and causing it to wrinkle faster.

Glycation also ages the body by creating oxidative stress. Oxidation eventually leads to a buildup of toxins called advanced glycation end products, or AGEs. The accumulation of some AGEs is normal, but eating poorly is like hitting the fast-forward button on aging.

That’s because AGEs build up in the body and damage our cellular engines: mitochondria. The loss of cellular energy gives rise to such age-related complaints as loss of memory, hearing, vision, and stamina.

Some findings show AGEs build up in the brains of people with Alzheimer’s (increasingly referred to as “type 3 diabetes”). AGEs are also linked to the more rapid development of arterial plaque in people with heart disease, and appear to be associated with Parkinson’s disease as well.

The Fix

If you can go cold turkey on processed sugar, great. If not, cut back as far as you can. For the sweets you do eat, choose foods made with less heavily processed natural sweeteners, such as honey or maple syrup, instead of refined (white) sugar.

“Although natural sugars aren’t much better for your health, foods sweetened naturally tend to be less refined and contain other whole-food ingredients, and that is beneficial for reducing sugar load,” says Talbott.

Cut back on the sugar you use in recipes at home, and try adding less sugar to your coffee, tea, and other frequently consumed beverages.

One more tip: Don’t swap your sugar for artificial sweeteners. There’s evidence that they can do as much or more damage to your health in other ways (see “Secret Ingredients“).

Body-Aging Habit No. 3: Waiting to Eat Until You’re Famished

Big Offender: Crashing and spiking blood sugar, which wreaks hormonal havoc, promotes inflammation, and drives unhealthy food cravings.

How It Ages You: When the stomach is empty, its secretion of ghrelin, also called the “hunger hormone,” doubles. When the stomach is full, secretion of ghrelin slows and its hormonal opposite, leptin, signals that the body is satiated. But it can take 20 minutes for this process to unfold. During this time, it’s easy to overeat.

“Going for a long period without food and then gorging is the textbook way to gain weight,” says Talbott. “When you gorge, you eat more, your blood sugar spikes higher, and your body stores more calories for later because it’s in feast-or-famine mode.”

Significantly, frequent blood-sugar spikes are linked to insulin resistance, a precursor to type 2 diabetes and metabolic syndrome, and to bodywide inflammation.

“As we get older, we get metabolic-ally less flexible, meaning our bodies have difficulty using insulin to shift micronutrients from the bloodstream into cells,” says Deanna Minich, PhD, FACN, CNS, author of The Complete Handbook of Quantum Healing. “An inability to use insulin effectively hastens aging by zapping a person’s vitality, strength, and sex drive.”

The Fix

Don’t wait until you’re voracious to eat. Tune in to your body and get to know what it feels like to be moderately hungry, says Swift: “This is the sweet spot.”

To satisfy moderate hunger, eat a healthy mix of macronutrients — proteins, fats, and nonstarchy carbs. This trifecta offers high-quality, long-lasting energy. Swift recommends hummus and veggies, nut butter and apple slices, or nuts and seeds mixed with a little dried fruit.

Body-Aging Habit No. 4: Eating Too Many Refined Carbs

Big Offender: Refined, starchy carbohydrates (healthy carbs stripped of all the good stuff).

How It Ages You: Refined carbs are simply sugars in disguise. “Starch turns into sugar the minute it hits your bloodstream,” says Lodge. Beyond causing glycation (see Habit No. 2), refined carbs set the stage for insulin resistance.

Lodge notes that the human body evolved with a limited ability to break down sugars (and limited exposure to sugar in concentrated forms), so it hasn’t kept pace with the modern diet.

After a meal laden with refined carbohydrates, the body’s blood-sugar levels soar, and the pancreas sprays insulin into the bloodstream to help cells convert the food’s energy (glucose) into fuel. It often miscalculates and releases too much insulin.

As a result of this excess insulin, blood-sugar levels drop, and 30 minutes later you’re hungry again. “The body wasn’t designed for this yo-yo effect,” says Lodge. The technical term for this effect is “insulin resistance”; it’s a precursor to such age-related diseases as type 2 diabetes, metabolic syndrome, and heart disease.

In addition, because simple carbohydrates burn quickly, they leave nothing to nourish the health-promoting microbes that reside in our large intestines.

“We’ve learned a lot lately about the importance of carbohydrates to our gut ecosystem,” says Swift, who explains that healthy gut flora feed on fermentable fibers and resistant starches found in many complex carbohydrates.

These so-called indigestible carbs produce short-chain fatty acids that in turn affect glucose regulation, blood-sugar regulation, and insulin resistance. “Eating the right type of carbs is critical to supporting this milieu,” she says.

The Fix

Stick to whole-food carbohydrates, such as vegetables, legumes, and whole-kernel grains. Because whole-kernel grains are left intact (versus being pulverized into flour or stripped of their germ and bran), they take longer for the body to digest, and the sugar is released in a slow, steady stream.

The resistant starches and fermentable fibers in complex carbs also feed your hungry gut flora and influence signaling molecules that help moderate insulin release.

“These foods provide critical information for your body,” says Swift. “They’re our primary currency for aging well — one of the best investments we can make.”

Body-Aging Habit No. 5: Eating When You’re Stressed

Big Offender: Cortisol, the stress hormone secreted by your adrenal glands.

How It Ages You: Stress hormones (automatically released by the body under all kinds of stressful circumstances) are antithetical to digestion in a couple of ways.

First, the release of adrenaline and cortisol — fight-or-flight chemicals — diverts blood toward your limbs and away from your stomach and intestines. As a result, food may ferment in the intestines, upsetting the balance of good and bad bacteria, says Lodge, and hindering the intestines’ ability to break down and absorb key nutrients like vitamin B12.

“Eating when you’re stressed damages your body and locks out the repair crew,” says Lodge.

Stressed or distracted eating can also lead to unconscious eating. You may eat more than you intended or eat foods you wouldn’t have chosen under better circumstances.

The Fix

If you are stressed and tempted to raid the cupboard, Lodge says, drink a glass of water and go for a five-minute walk instead.

Whenever possible, eat in places where you feel calm and happy. At home, create a relaxing atmosphere: Set the table and light a candle, suggests Kevin Spelman, PhD, an adjunct professor at the National College of Natural Medicine in Portland, Ore. “Just as your senses assimilate that environment in a pleasant way, your body will assimilate food in a more efficient way.”

Body-Aging Habit No. 6: You eat a lot of roasted, grilled, or deep-fried food

Big Offender: Advanced glycation end products, known as AGEs.

How It Ages You: AGEs are toxins that speed aging by causing oxidative stress and inflammation. You make some AGEs naturally, but most enter your body via food. The biggest culprits are foods that are deep-fried, broiled, roasted, or grilled. Those sear marks on a grilled steak, the crispy skin on a piece of fried chicken, even the browned edges of roasted vegetables are all signs of AGEs in your food.

“Most people don’t realize aging well is not just about choosing healthy foods, but about preparing them in healthy ways,” says Deanna Minich, PhD, FACN, CNS, and author of The Complete Handbook of Quantum Healing.

Your skin is a good place to see AGEs at work. As you age, AGEs accumulate in the skin’s tissue and break down collagen proteins, resulting in wrinkles. But the skin is just the beginning.

High AGE levels in the body are linked to neurodegeneration, tendon dysfunction, and blood-vessel stiffness. Indeed, most age-related illnesses — including Alzheimer’s, heart disease, stroke, and osteoporosis — are connected to high amounts of AGEs.

The Fix: Reduce AGEs in your diet by eating more raw fruits and vegetables, legumes, and whole grains. Cook meat and veggies at lower temperatures, utilizing techniques that rely on moisture, which keeps AGEs at bay. For example, steam or blanch vegetables, or sauté lightly with a little olive oil. Seafood can be steamed, chicken can be poached, and red meat can be stewed or braised. (For tips on cooking techniques, see “Cooking Chemistry“.) “Go low and go slow,” says Swift.

If loss of flavor is a concern, Swift recommends marinades: “Not only do marinades — particularly those made with vinegars or lemon juice — add flavor, they also help lower your body’s levels of AGEs.”