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True or False? Low Carb Diets Are Good for You!

by | Last updated Jun 17, 2025 | Grains, Nutrition

You have seen it on Facebook postings, read it on the internet, heard it on the news: “Carbs are bad for you if you are trying to lose weight.” Pundits advocating a low-carbohydrate diet condemn the consumption of starches. They say that even whole grains sabotage your health. Consuming a high-protein diet assists in weight loss, but is it the best choice? Does the type of protein we eat make a difference in our desired goal to achieve health?

This generality of villifying all carbs is not accurate. No doubt about it, consuming sugar, eating refined grains, and fried potatoes increases the risk for obesity, diabetes, liver damage, and a decline in kidney function, but that is not the whole picture. While simple carbohydrates like sugar, high fructose corn syrup, and desserts are detrimental when consumed regularly or excessively, good carbs from whole grains, whole fruits, and whole vegetables are essential for brain health. As important as protein and healthful fats are, we still need to eat good carbs for optimal brain performance. Here is the evidence:

Low-Carb Diets Reduce Brain Function.

Low-carb diets reduce cognitive functioning. Glucose from carbohydrate is the brain’s preferred fuel. While the brain uses glucose as its primary fuel, it cannot store it. A reduced intake of carbohydrate consequently reduces the brain’s source of energy.  Research fromTufts University shows that when dieters eliminate carbohydrates from their meals, they perform more poorly on memory-based tasks than when they reduce calories, but maintain carbohydrates. Women dieters were divided into two groups. One group ate a low-calorie diet while the other consumed a low-carb diet. They took tests to measure their cognitive performance before and after their three-week diets.

Low-carb dieters showed a gradual decrease in the memory-related tasks compared with the low-calorie dieters. Reaction time for those on the low-carb diet was slower and their visuospatial memory was not as good as those on the low-calorie diet. 1 However, low-carb dieters responded better than the low-calorie dieters during the attention vigilance task.

How Much Carbohydrate Should We Eat?

The amount of carbohydrates depends on the type and the food sources of carbohydrates we eat! A meta-analysis of 43, 000 people 2 (after adjusting for age, sex, race, total energy intake, education, exercise, income level, smoking, and diabetes.) found:

  1. Low and high intakes of carbohydrates were linked with an increase in mortality. In contrast, the consumers of a moderate amount of carbohydrates had the lowest risk of mortality. Participants who ate a moderate amount of carbohydrates (40 to 60% of total caloies) lived 4 years longer than those who ate a low-carb diet and 1 year longer than those who consumed a high-carb diet. In this particular study, a low-carbohydrate intake was defined as getting less than 40% of the total calories from carbohydrates.
  2. Low-carb diets that replace carbohydrates with proteins and fats from plant sources were associated with a lower risk of mortality when compared to those that replace carbohydrates with proteins and fats from animal sources.

However, the types of carbohydrates eaten in this study were not clarified.

Low-Carb Diet and Heart Health:

People getting a low proportion of their daily calories from carbohydrates such as grains, fruits, and starchy vegetables are significantly more likely to develop atrial fibrillation (AFib), the most common heart rhythm disorder. Low-carbohydrate diets were associated with increased risk of incident atrial fibrillation, regardless of the type of protein or fat used to replace the carbohydrate.3

Not All Starches Are Created Equally

Rapidly digested starch breaks down quickly into simple sugars. The starch in white potatoes and refined baked goods digests very quickly, providing readily available glucose for the body’s needs.

Slowly digested starch breaks down into glucose over time in the small intestine, up to two hours. Other foods with high starch content, such as beans, barley, or long-grain brown rice, are digested even more slowly and cause a slower and lower rise in blood sugar.

Resistant starches are found in foods that often have a fibrous “shell,” making it harder for the digestive enzymes to reach them. Legumes are the best source of resistant starch, followed by grains. If you let your potatoes and grains cool after you cook them, they will have more resistant starch.

Health Benefits of Resistant Starch

Better Blood Chemistry

A meta-analysis revealed that consuming foods rich in resistant starches reduces the total and LDL cholesterol levels.4 Resistant starch seems to improve the ability of the cells to respond to insulin. Studies show that resistant starch consumption is linked to improved mineral absorption, especially calcium and magnesium.

Promotes Better Appetite Control

Resistant starch, when combined with protein, produces more satiety, or satisfaction, from a meal, improves fat burn, and is associated with less fat storage after that meal.5

Type 1 resistant starch (found in grains, seeds, and legumes) improves the ability of the cells to respond to insulin and improves fat burn.6 Resistant starch has been associated with an increase in certain gut bacterial populations that have been negatively correlated with type 2 diabetes.6 To get the most amount of resistant starch, let the grains cool before eating them.

Resistant starch reduces the pH level in the colon and substantially decreases inflammation, which may reduce one’s risk for colon cancer.7 8 

Benefits of Low-Glycemic Carbs

True or False? A calorie from one food is the same as a calorie from another food. Not exactly true. Low-carb diets do seem to help weight loss, but the truth is that any diet that prevent the sudden surges in blood sugar helps weight loss. 9 It does not have to be a low-carb diet.

The glycemic index (GI) is a helpful system that allows you to see how the fruits, vegetables, and other carbohydrates you eat affect your blood sugar levels. It ranks food on a scale of 0 to 100. The diet that emphasizes low glycemic foods also results in weight loss. How? Foods with higher ratings of 70 to 100 produce a spike in your blood sugar levels and trigger your pancreas to release large amounts of insulin. This hormone facilitates the transport of glucose and fatty acids into your cells to be used as energy. While we need appropriate amounts of insulin, high levels of insulin circulating through your blood promote fat synthesis and make it difficult for your body to burn stored fat.

Low-GI foods release glucose more slowly and steadily. This consequently results in better blood glucose readings after a meal and prevents sudden surges of blood sugar and steep insulin levels. Studies show that the low-glycemic index diet has similar metabolic benefits to the very low-carb diet, with two important differences. The low-glycemic diet does not produce the stress and inflammation seen on low-carb diets. In contrast, low-carb diets increase cortisol levels and C-reactive protein, a marker for inflammation.9

A low-GI diet offers another advantage. After weight loss, the rate at which people burn calories slows. 10 This makes it difficult for the needed weight loss to be maintained. A low-glycemic diet is effective at burning calories after weight loss is achieved.11

Additionally, ingesting foods at breakfast that have a low glycemic index may help prevent a spike in blood sugar throughout the morning and after the next meal of the day. 12 Because low-GI foods are usually rich in fiber, they stabilize the blood sugar and promote satiety. Moreover,eating low GI foods increases the appetite-suppressing hormone GLP-1.13

What Foods Score Low on the GI Index?

  • Most vegetables: cruciferous vegetables, salad veggies, greens, onions, eggplant, squash, sweet potatoes, carrots
  • Most whole grains: rye, barley, oats, spelt, millet, long-grain brown rice, whole grain pasta
  • Legumes: kidney beans, lentils, lima beans, split peas, black-eyed peas, green peas, almonds, peanuts, chickpeas
  • Seeds: chia, flax, sunflower, pumpkin, sesame
  • Fruits: cherries, prunes, dried apricots, grapefruit, apples, berries, pears

Pros and Cons of A High-Protein Diet

Eating a protein-rich breakfast curbs hunger and reduces unhealthy snacking on high-fat or high-sugar foods in the evening. A higher protein intake increases the hunger-fighting hormone known as peptide YY. 14 Eating more protein in the morning rather than packaged cereal also helps to prevent blood sugar spikes.

There are dangers in adopting a high-protein diet, especially if it is animal protein. Even though high-protein diets like Atkins do produce weight loss, rodent studies indicate that this type of diet is not the best for health. When mice were fed a high protein/low carbohydrate diet, they had brains five percent lighter than all the other mice, and regions of their hippocampus (important for mood and memory) were less developed. In other words, a high-protein diet shrinks the brain. 15

A diet rich in animal proteins during middle age makes you nearly twice as likely to die young and four times more likely to die of cancer. This mortality factor is comparable to smoking. 16

Replacing animal protein with legumes is a better, safer route. A systematic review and meta-analysis of all available clinical trials found that people felt 31 percent fuller after eating on average 160 grams (l serving) of dietary pulses compared with a control diet. 17 As previously mentioned, legumes score low on the glycemic index and are high in fiber.

Something Better: The Total, Whole-Food, Vegetarian Diet

People shed more weight on an entirely plant-based diet, even if carbohydrates are included. Other benefits of eating a vegan diet include decreased levels of saturated and unsaturated fat, lower body mass indices, and improved intake of macronutrients. The ability to shed weight is faster for those who adopt a total vegetarian diet than for those consuming meat and dairy, or even those who eat a mostly vegetarian diet. One study showed that at the end of six months, individuals on the vegan diet lost more weight than those individuals who ate a mostly plant based diet and those who were omnivores, by an average of 4.3%, or 16.5 pounds.18 A meta-analysis of 12 studies demonstrated that vegetarian diets are more effective than non-vegetarian diets for weight loss.19

In a 2020 meta-analysis of 38 studies lasting 6–12 months and including 6,499 participants, low-carbohydrate diets, defined here as <40% of energy from carbohydrate, led to a small weight loss, compared with low-fat diets, defined as <30% of energy from fat.31 Evidence suggests a low-fat, plant-based diet may improve satiety more than a low-carb diet.20

Disclaimer: The information in this article is helpful and educational. It is not the author’s or authors or Wildwood Health Institute’s intent to substitute the blog article for diagnosis, counseling, or treatment by a qualified health professional.

 

  1. Tufts University. “Low-carb Diets Can Affect Dieters’ Cognition Skills.” ScienceDaily. ScienceDaily, 15 December 2008. www.sciencedaily.com/releases/2008/12/081211112014.htm[↩]
  2. Seidelmann, Sara B. et al. Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis. The Lancet Public Health, 2018; DOI: 10.1016/S2468-2667(18)30135-X[↩]
  3. American College of Cardiology. “Low-carb diet tied to common heart rhythm disorder: Study suggests using caution when restricting carbohydrates for weight loss.” ScienceDaily. ScienceDaily, 6 March 2019. https://www.sciencedaily.com/releases/2019/03/190306081652.htm[↩]
  4. Yuan HC, Meng Y, Bai H, Shen DQ, Wan BC, Chen LY. Meta-analysis indicates that resistant starch lowers total serum cholesterol and low-density (LDL )cholesterol. Nutr Res. 2018 Jun;54:1-11. doi: 10.1016/j.nutres.2018.02.008. Epub 2018 Mar 5. PMID: 29914662.[↩]
  5. Gentile, C.L., et al. Resistant starch and protein intake enhance fat oxidation and feelings of fullness in lean and overweight/obese women. Nutr J 14, 113 (2015). https://doi.org/10.1186/s12937-015-0104-2[↩]
  6. Pugh JE, Cai M, Altieri N, Frost G. A comparison of the effects of resistant starch types on glycemic response in individuals with type 2 diabetes or prediabetes: A systematic review and meta-analysis. Front Nutr. 2023 Mar 27;10:1118229[↩][↩]
  7. Hylla S, et al., Effects of resistant starch on the colon in healthy volunteers: possible implications for cancer prevention. Am J Clin Nutr. 1998 Jan;67(1):136-42. doi: 10.1093/ajcn/67.1.136.[↩]
  8. Zimmerman, M. A., et al. (2012). Butyrate suppresses colonic inflammation through HDAC1-dependent Fas upregulation and Fas-mediated apoptosis of T cells. American journal of physiology. Gastrointestinal and liver physiology, 302(12), G1405–G1415. https://doi.org/10.1152/ajpgi.00543.2011[↩]
  9. Children’s Hospital Boston. “Dieting? Study challenges notion that a calorie is just a calorie.” ScienceDaily. ScienceDaily, 26 June 2012. www.sciencedaily.com/releases/2012/06/120626163801.htm[↩][↩]
  10. Ebbeling CB. Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance. JAMA, June 27, 2012 DOI: 1001/jama.2012.6607[↩]
  11. Children’s Hospital Boston. “Dieting? Study challenges notion that a calorie is just a calorie.” ScienceDaily. ScienceDaily, 26 June 2012. www.sciencedaily.com/releases/2012/06/120626163801.htmb[↩]
  12. Institute of Food Technologists (IFT). “Glycemic index foods at breakfast can control blood sugar throughout the day.” ScienceDaily. ScienceDaily, 30 March 2012. www.sciencedaily.com/releases/2012/03/120330110204.htmsciencedaily.com/releases/2012/03/120330110204.htm. [↩]
  13. Society for Endocrinology. “Scientists Discover Why A Low GI Meal Makes You Feel Full.” ScienceDaily. ScienceDaily, 18 March 2009. www.sciencedaily.com/releases/2009/03/090317201139.htm[↩]
  14. Cell Press. “Eating Protein Boosts Hormone That Staves Off Hunger.” ScienceDaily. ScienceDaily, 6 September 2006. www.sciencedaily.com/releases/2006/09/060905225848.htmb[↩]
  15. BioMed Central. “Alzheimer’s Researchers Find High Protein Diet Shrinks Brain.” ScienceDaily. ScienceDaily, 21 October 2009. www.sciencedaily.com/releases/2009/10/091020192206.htm[↩]
  16. University of Southern California. “Meat and cheese may be as bad for you as smoking.” ScienceDaily. ScienceDaily, 4 March 2014. www.sciencedaily.com/releases/2014/03/140304125639.htm[↩]
  17. Siying S. L. Dietary pulses, satiety and food intake: A systematic review and meta-analysis of acute feeding trials. Obesity, 2014; 22 (8): 1773 DOI: 1002/oby.20782[↩]
  18. Turner, Gabrielle M. Comparative effectiveness of plant-based diets for weight loss: A randomized controlled trial of five different diets. Nutrition, 2014; DOI: 1016/j.nut.2014.09.002[↩]
  19. Huang, R-H. et al. Vegetarian Diets and Weight Reduction: A Meta-Analysis of Randomized Controlled Trials. Journal of General Internal Medicine, June 2015.)http://DOI: 1007/s11606-015-3390-7)[↩]
  20. Academy of Nutrition and Dietetics Evidence Analysis Library. In Adults, How Effective, in Terms of Weight Loss and Maintenance, are Low Carbohydrate Diets (Defined as <35% kcals From Carbohydrate)? (2006) [↩]

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