Skip to content

20 Health Issues That Are a Sign of a Bad Diet

Relying on fast food for fuel can result in more than just belly fat—it can land you in the MD's office.

We usually associate a "bad diet" with belly fat, but there's a surfeit of serious health issues that are closely linked to nutritional deficiencies. Sure, you may notice the number on your scale hiking up after digging into one-too-many bacon cheeseburgers and ice cream sundaes; however, you may need a doctor's office visit to ferret out the more insidious ailments. Other issues—such as your risk for cardiovascular disease—aren't as visually alarming as your muffin top but require medical acknowledgment nonetheless.

To get a hold of your health and find out which diet-derived issues you should keep an eye out for, we spoke to experts in the health and wellness sphere about the top health complications that signal a bad diet. And while you're reading up, be sure to try out these 21 Best Healthy Cooking Hacks of All Time.


Woman's hands hold back spine suffering pain wear.

"Osteoporosis occurs because the bones become brittle and weak and are at higher risk of breaking. There are a few different risk factors that can cause osteoporosis. A few of them are diet-related such as insufficient calcium and vitamin D intake as well as an increase in drinking alcohol. The best sources of calcium are found in vegetables but can also be found in items such as low-fat milk [and] yogurt. Depending on how low one's calcium and vitamin D levels are, vitamin supplements may also be necessary."

—Shannon Cook, NP-C

Eating Disorders

Woman barely eating cucumber

"A diet-gone-wrong can trigger symptoms of an eating disorder. Severe food restriction can trigger obsessive thoughts and behaviors leading to an increased desire for thinness, resulting in anorexia. Starving the brain of essential nutrients can trigger an obsession with food that can lead to binging, with the resultant shame triggering a desire to purge. Further, a binge can trigger inflammation in the body and brain, which the body sends out stress hormones to counteract, resulting in an addictive cycle. Any time the body is deprived of specific nutrients needed for optimal functioning, the body and brain will spiral into a self-protective mode. The body has natural compensatory mechanisms against food restriction and excessive weight loss, so any diet-gone-wrong can have detrimental effects on the body and the brain."

—Dr. Angela Grace, PhD

Chronic Constipation

Woman stomach cramps

"Constipation may not sound like a serious health complication, but chronic constipation affects many people and can be quite uncomfortable and affect quality of life. Many factors contribute to constipation, including not getting enough fiber and/or water in the diet. Plant-based foods such as fruits, vegetables, whole grains, and pulses are loaded with vitamins, minerals, phytonutrients, and fiber. It's recommended to aim for 25-30 grams of fiber per day, but the average American is only getting 15 grams, and many less than that. Increase your fiber intake gradually to avoid gas and bloating. Water is essential for moving fiber through the GI tract so when you increase fiber, make sure to also increase water intake. Eating your water is a good tactic, too—think broth-based soups, and certain high-water fruits and vegetables, like cucumbers, lettuces, tomatoes, green peppers, watermelon, grapefruit, and cantaloupe."

—Rachel Begun, MS, RDN


Step on scale

"It is imperative for the body to have the right balance of macronutrients (protein, fat, and carbohydrates) as well as micronutrients and electrolytes for their individual metabolic needs. If the body does not have the right balance or type of fuel, it can result in systemic deficits as well as weight management issues such as obesity. Metabolism is a complicated interaction of cellular reactions, if those nutrients are not there to act as co-factors (helpers in the reactions), a domino effect happens in that metabolic pathway leading to a bevy of health conditions. It all matters—amount, type and quality of nutrient intake."

—Monique Richard MS, RDN, LDN

Dark, Pungent Urine

Door handle open to toilet can see toilet

If you're experiencing "thirst, less frequent urination, more concentrated urine (darker color, stronger smell)," you may need more fluids, asserts Kerkenbush. "How much? The Institute of Medicine recommends that women get about 11 cups of water from food and drink each day, and men get about 16 cups daily. Skip soda, sugary coffee, and energy drinks in favor of water, non-fat milk or unsweetened tea."

Increased Breast Cancer Risk

woman in white t-shirt with breast cancer pink ribbon

"The vast majority of chronic diseases that afflict Americans—cardiovascular disease, type 2 diabetes and many types of cancer—are the result of decades' worth of poor diet and insufficient exercise. In fact, national health statistics estimate that two-thirds of chronic diseases afflicting Americans are linked back to lifestyle factors, including eating and exercise patterns. Alcohol and breast cancer risks are associated with women who have a specific genetic predisposition. In fact, most health professionals tell women who are at risk for breast cancer to avoid drinking alcohol."

—Julie Upton, MS, RD, and co-founder of Appetite for Health


Woman with stomach pain

"Certain foods can weaken the 'doorway' between the esophagus and stomach, thus making reflux of stomach contents into the esophagus more likely. These foods are chocolate, caffeine, mint. Acidic foods can also make GERD worse because higher acid content [equals] more burning. A lack of B vitamins can affect the growth of the wall of the esophagus (and stomach) making it more fragile."

—Susan L. Besser MD, FAAFP, Diplomate American Board of Obesity Medicine

Increased Risk of Heart Disease

Man having a heart attack

"A poor diet high in sugar and saturated fat is consistently linked to plaques in the arteries that lead to heart attack, stroke, abnormal blood lipids or atherosclerosis," Upton tells us. To keep your ticker in top shape, stock up on these 20 Best Foods for Your Heart.


Man with diabetes

"All foods are eventually converted to sugar (the body's energy source), except pure protein which is used in a different way. Thus, too much intake of any food can make diabetes worse. However, pure sugars can cause the most dramatic sugar fluctuations in the body and are used most rapidly. Complex carbohydrates and other foods (yes, including vegetables) are absorbed more slowly, which gives the body more time to digest/use them."

—Susan L. Besser MD, FAAFP, Diplomate American Board of Obesity Medicine


Depressed man

"I think it's important to talk about a diet rich in healthy fats, omega-3 fatty acids, particularly. When we are lacking in omega-3s and other nutrients like magnesium, we tend to see an increase in depressive moods, mood swings, and general gloominess. The brain thrives on these fatty acids to function properly and enhances brain function, particularly in regards to controlling mood. Good sources of omega-3s include salmon, cod, fish oil, walnuts, chia seeds, or flax. Focus on eating a diet that is balanced in complex carbohydrates such as whole grains, sweet potatoes, or starchy vegetables; protein such as lean meats, beans, eggs, and yogurt; and healthy fats including avocado, olive oil, nuts, and seeds."

—Carrie Moody, RDN

Hair Loss

Man looking at hair

"Insufficient intake of protein can lead to damaged hair follicle structure and hair loss. Iron deficiency can also lead to hair loss," Moody shares. To keep your locks long and strong, discover these 23 Doctors' Own Tips for Healthy Hair.

Non-Alcoholic Fatty Liver Disease

Man eating in car

"NAFLD or NASH, otherwise known as fatty liver in children, adolescents, and adults [is] due to poor dietary choices related to excess sugary beverages, convenience foods, and foods high in saturated fat."

—Monique Richard, RDN, LDN

Your guide to the anti-inflammatory diet that heals your gut, slows the signs of aging, and helps you lose weight.

Poor Wound Healing

Woman checking skin

"Inadequate protein (eggs, dairy, lean meats, nuts, seeds, fish, beans, and legumes), inadequate calories, and inadequate Vitamin C" intakes can lead to slow-healing wounds, according to Becky Kerkenbush, RD-AP, CD-member of the Wisconsin Academy of Nutrition & Dietetics. Besides noshing on sufficient lean protein, make sure you're getting your daily intake of vitamin C via foods such as guava, red bell peppers, and Brussels sprouts.


Numb hands

To prevent anemia, "I would recommend including iron-rich foods such as spinach, lean protein, beans, prunes, lentils, and tofu in a balanced diet. If iron supplementation is necessary, I recommended working with a physician to provide recommended safe amounts. I also would advise eating less fast food, empty-calorie junk foods, and focusing on increasing fruits, vegetables, whole grains, and lean protein. Make sure you are drinking adequate amounts of water as well!"

—Haley Hughes MS, RD, CDE

Weak Immune Systems

Woman sick cold

"Weak immune systems have been linked to poor diets. Without adequate nutrition, it's harder for your body to respond to infections or fight illness. Protein, zinc, vitamin A, C, and E are important nutrients to include in your diet by choosing nutrient-dense foods regularly. Lean protein examples are poultry without the skin, eggs, lean beef or pork, fish, and tofu. For zinc, try incorporating seafood two to three times per week, nuts and seeds, spinach, and lean beef. For vitamin A, look for those colorful orange foods like carrots and sweet potatoes. For vitamin C, [look for] citrus, red peppers, kale. Leafy greens, nuts, seeds, and avocados [are great sources of vitamin E]."

—Haley Hughes, RD, CDE

Brittle Nails

Hand with brittle nails.

If you're suffering from splitting, brittle nails, "it usually comes down to people not including enough fruits and vegetables in their diet. Research shows, just 12.2 percent of American adults ate their recommended daily dose of fruit in 2015, and only 9.3 percent ate the suggested amount of vegetables that year, according to a report from the U.S. Centers for Disease Control and Prevention. The 2015-20 Dietary Guidelines for Americans advise adults eat the equivalent of one-and-a-half to two cups of fruit and two to three cups of vegetables daily."

—Haley Hughes, RD, CDE

Adult Acne

middle age woman to see a mirror

"Research has shown that foods in the Western diet (highly processed and high sugar foods) can play a huge role in adult acne because they promote inflammation. Some of the biggest culprits include cow's milk, junk food, and processed foods. Limit white bread, white potatoes, and junk food and instead eat whole grains, sweet potatoes, beans, and vegetables. Limit cow's milk (hormones in milk likely the culprit behind skin inflammation/acne) and try a milk alternative such as unsweetened almond milk or cashew milk. Foods high in omega-3 fatty acids like fish, and those high in antioxidants and vitamin C can help to combat inflammation in the skin and throughout the entire body."

—Carrie Moody, RDN


Burger and beer

"Gout is exacerbated by foods high in purines like red meat, and alcohol also it's noted that things like asparagus are also high in purines. Foods like red meat or alcohol also cause inflammation, so it's a double whammy."

—Vanessa Rissetto, RD

Peptic Ulcers

Stomach pain

"Peptic ulcers are 'open sores that develop on the inside lining of your stomach and the upper portion of your small intestine,' according to Mayo Clinic. Taking certain medications regularly such as Non-Steroidal Anti-inflammatory Drugs (NSAID) can be direct causes of ulcers. Examples of these medications include ibuprofen, aspirin, and Aleve. Although ulcers are not caused by poor dietary choices, they can be exacerbated by them. The stomach is already an acidic environment. Certain foods and dietary habits that can cause an increase in acid buildup—and should, therefore, be limited—include caffeine, fried foods, spicy foods, smoking, and alcohol."

—Shannon Cook, NP-C

Poor Dental Health

Flossing teeth

"When I examine a patient by with dental decay of teeth and gums, cavities, gingival inflammation (inflamed gums), hypocalcification of the enamel (white spots on teeth and lesions at gum line), and periodontal disease, the first question I ask is, 'What's your diet?' The typical answer I get is 'chips, soda, sports drinks, and candy.' Many patients who show these symptoms and have a poor diet, also don't take care of their teeth. Stop drinking soft drinks, energy drinks, and sports drinks. These beverages have a high sugar content and, in our patients, we see these drinks as a link to poor dental health."

Bryan Simone, DDS

"Eat a well-balanced diet that includes more non-processed, non-sugary foods. Fruits, vegetables, and lean protein are best. This doesn't mean that you can never again eat highly processed, high-sugar foods. It's okay every once in a while, but you need to focus on moderation. Get regular dental check-ups and cleanings. Your mouth is the doorway to your overall health."

—Kyle Lowe, DDS

April Benshosan
April is a born-and-raised Brooklynite who has a passion for all things health, wellness, and tastebud-related. Read more about April
Filed Under