Taylor Stinson's Sheet Pan Greek Chicken Meal Prep Bowl with lemon and oregano marinade is a low-carb lunch or dinner idea that's ready in 30 minutes.Taylor Stinson/Canadian Press
Many studies have demonstrated the effectiveness of low-carbohydrate diets for short-term weight loss. However, few studies have investigated how well such diets continue to reduce weight over the long term.
Now, a new study led by researchers at Harvard University's TH Chan School of Public Health has detailed answers.
It turns out that not all low-carb diets are created equal when it comes to losing weight.
latest research
The study, published Dec. 27 in JAMA Network Open, analyzed data from 123,332 healthy adults with an average age of 45. We are participating in one of three large ongoing studies in the United States: the Nurses' Health Study, the Nurses' Health Study II, and the Health Professionals Follow-up Study.
Participants were followed from 1986 to 2018. Dietary information and weight were collected every 4 years.
The researchers created five categories of low-carbohydrate diets based on the participants' dietary intake, each emphasizing a different composition and quality of macronutrients (protein, fat, carbohydrates).
The researchers then scored each participant on how well they adhered to one of five low-carbohydrate diet categories.
A “completely low-carbohydrate diet” simply refers to reducing overall carbohydrate intake, regardless of macronutrient quality.
An “animal-based low-carbohydrate diet” emphasizes animal protein and fat, while a “plant-based low-carbohydrate diet” emphasizes plant-based protein and fat.
A “healthy low-carb diet” that focuses on plant-based proteins, healthy fats, and whole grains. An “unhealthy low-carbohydrate diet,” on the other hand, emphasized animal protein, unhealthy fats, and refined carbohydrates.
All low-carbohydrate diets contain 38 to 40 percent of your daily calories from fat.
Healthy and unhealthy low-carbohydrate diets: 4 years of weight change
The study found that a healthy low-carbohydrate diet consisting of high-quality protein, fat, and carbohydrates led to slower long-term weight gain than four other low-carbohydrate diets.
Among participants who followed an unhealthy low-carbohydrate diet, those who increased their adherence to such a plan over four years experienced even greater weight gain.
Compared to those who adhered least to this eating pattern, those who adhered the most gained an average of 5.1 pounds more over four years.
In contrast, healthy low-carbohydrate dieters whose adherence scores increased the most over four years lost an average of 4.9 pounds compared to those whose adherence scores decreased the most.
This result was most pronounced among participants who were younger than 55 years of age, overweight or obese, and/or had low physical activity.
These findings highlight the importance of considering the quality of macronutrients in low-carbohydrate diets for weight management.
strengths and limitations
Researchers looked at the link between low-carbohydrate diets and long-term weight change across a broad spectrum, considering not only the quantity but also the quality of macronutrients.
Other notable strengths are the large sample sizes and long follow-up periods of the three studies.
Limitations include the observational nature of the study, which cannot reliably prove that a healthy low-carbohydrate diet reduces long-term weight gain.
consistent with past research
This isn't the first study to suggest that a high-quality diet can make a difference in weight management.
An analysis of the DIETFITS trial published last year found that people with both high diet quality and dietary adherence were most successful in losing excess weight, regardless of whether they followed a low-carbohydrate or low-fat diet.
And results from the PREDIMED trial showed that a Mediterranean diet (40% carbohydrates) rich in extra virgin olive oil, fruits, vegetables, whole grains, beans and lentils led to greater weight loss compared to a low-calorie diet. consistently shows that it leads to A diet high in fat (43 percent carbohydrates).
A high-quality diet provides more fiber, which can promote satiety and reduce overall calorie intake.
Research has also shown that consuming healthy vegetable oils from nuts, seeds, and olive oil can improve weight.
On the other hand, diets high in saturated fat from animal foods are associated with increased risk of inflammation, insulin resistance, and weight gain.
Meals high in refined grains and sugar can cause rapid fluctuations in blood sugar levels, leading to hunger and overeating.
Key ingredients of a healthy low-carbohydrate diet
Emphasize plant-based proteins like beans, lentils, bean pasta, edamame, tofu, and nuts.
Lean animal proteins include chicken, turkey, seafood, plain low-fat Greek yogurt, cottage cheese, and egg whites. Limit red and processed meats.
Eat small portions of whole grains such as brown or red rice, quinoa, farro, millet, and oats.
Eat lots of non-starchy vegetables (leafy greens, broccoli, cauliflower, peppers, etc.). Potatoes, green peas, corn, parsnips, and winter squash are starchy.
Add some whole fruit as well. Berries, pomegranate seeds, cantaloupe, kiwi, and citrus fruits are low in carbohydrates.
Choose unsaturated vegetable oils. Extra virgin olive oil, avocado oil, peanut oil, nuts and seeds are good choices.
Leslie Beck, a Toronto-based dietitian in private practice, is Medcan's Director of Food and Nutrition. Follow her on X @LeslieBeck
