The concept of clean eating involves eating minimally processed foods as close to their natural state as possible, such as fruits, vegetables, whole grains and legumes. However, there are major drawbacks to clean diets when they are very restrictive, such as reducing carbohydrates.
To better understand the nutrient gap in clean eating, we spoke with Lisa Dennis, RDN, LD/N, CEDS-C, director of nutrition at Monte Nido, an agency specializing in the treatment of eating disorders.
Q: How does it feel when someone cuts or cuts carbs in the name of clean eating?
Dennis: Carbohydrates are the body’s best energy source, and when dietary carbohydrates are insufficient, the body uses its stored form, glycogen, which causes initial loss of water weight.
Carbohydrates also provide energy, fiber, essential micronutrients, and are a major component of many delicious and satisfying meals. Limiting them can increase the risk of depression, low mood, binge eating, and overeating.
If you cut carbs, you may experience symptoms known as the “keto flu” that can leave you feeling really bad. With chronic restriction, fat is broken down into ketones for fuel. These metabolic changes can cause fatigue, headaches, dizziness, nausea, bad breath, decreased exercise performance, constipation, and altered hormone levels.While the body can adapt to use ketones as fuel in the absence of glucose, the transition takes time, during which energy levels are low.
Carbohydrate restriction can also affect hormones, digestion, electrolyte balance, and brain neurotransmitters, all of which can contribute to feeling physically and mentally unwell.
Q: Can clean eating affect your thyroid hormones? Could it make you feel worse?
Cutting carbs can also disrupt your thyroid hormones, and this can cause a kind of chain reaction in your body. Thyroid hormones regulate metabolism, body temperature, heart rate, and growth. Restricting carbohydrates can reduce your thyroid’s ability to convert T4 into more active T3.
When carbohydrate intake is too low, the body may reduce metabolism to conserve energy. It slows down the activity of the enzymes that convert T4 to T3, leading to low levels of active thyroid hormone and high inactive reverse T3 (rT3).
This can make you feel foggy, sluggish, and cold, even if thyroid hormone production itself is normal.
Q: Why is clean eating advice bad for your mental health?
Dennis: “Clean eating” frames food in ethical terms rather than focusing on overall and individual physiology. Nutrition is complex and only one part of health. Labeling food as “clean” implies that others are “unclean,” which implies guilt, hardship, and all-or-nothing thinking.
This mindset often reduces food variety, increases anxiety around social eating, and can quietly mask disordered eating patterns under the socially acceptable label. It also ignores cultural foods, economic conditions, and the fact that processing often improves food safety and nutrient availability.
Consider shifting your focus to your relationship with food—one built on trust, sufficiency, variety, and permission rather than guilt, fear, or rigid thinking.
It can be helpful to reflect on the food values that guide how and why you eat. These may include nutrition, satisfaction, communication, culture, access, or performance. When your food choices reflect a set of values, food becomes more flexible, consistent and sustainable, supporting your physical health and overall well-being.
If you need help doing this, a dietitian or nutritionist can help. “If you are concerned about your own or a loved one’s relationship with food and nutrition, there is help,” Dennis said.
If you or a loved one is living with an eating disorder, contact the Eating Disorder Helpline at 1-866-662-1235 for help and referrals.
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