In the quest to understand what constitutes a healthy diet, recent research highlights the potential benefits of a carbohydrate-reduced high protein (CRHP) diet for individuals with type 2 diabetes. The studies, published in The American Journal of Clinical Nutrition, suggest that this dietary approach may improve cholesterol levels, a significant concern for those at risk of heart disease. The Isoenergetic (Iso) and Hypoenergetic (Hypo) studies examined the effects of a CRHP diet, which consists of 30% of calories from carbohydrates, 30% from protein, and 40% from fats, compared to a conventional diabetes diet with 50% carbohydrates, 17% protein, and 33% fats.
The Iso Study involved 30 participants with type 2 diabetes who maintained their weight, while the Hypo Study included 72 participants aiming for weight loss. Both studies found that the CRHP diet effectively reduced triacylglycerol-rich lipoproteins (TRLs), apolipoprotein B, and low-density lipoprotein (LDL) cholesterol levels, while increasing high-density lipoprotein (HDL) cholesterol. This finding is crucial given that individuals with type 2 diabetes face a higher risk of developing high cholesterol, a known risk factor for heart disease.
“We know that patients with type 2 diabetes have higher risk for cardiovascular disease, regardless of the cholesterol levels, because the glucose in the blood can damage the lining of the blood vessels — we call it vascular injury,” said Monique Richard, MS, RDN, LDN.
Over recent years, growing evidence suggests that low-carbohydrate, high-fat diets might benefit people with type 2 diabetes. The reduction in intrahepatic triacylglycerol (IHTG) in both studies indicates that the CRHP diet may contribute to better liver health compared to the conventional diabetes diet. The inclusion of higher protein and fat intake could play a role in these positive outcomes.
“You would think that for something as important that we do every single day of our lives, multiple times a day, that we’d have clarity on what sort of a healthy diet to pursue, but there are actually still some questions outstanding, just because of challenges in doing research in this area. So any research studies that help us to determine what exactly is considered the best heart-healthy diet are appreciated,” said Monique Richard.
Traditionally, experts recommended a high carbohydrate and low fat diet with healthy carb sources and fiber-rich foods for managing type 2 diabetes. However, recent studies challenge this notion, presenting alternative dietary approaches. Research published in October 2024 indicated that following a low-carbohydrate diet might improve beta-cell function in people with type 2 diabetes. A study from January 2023 reported that 51% of participants achieved type 2 diabetes remission following a low-carb diet.
“Cutting out carbs completely typically is not beneficial in the long-term either. We need carbohydrates for fuel, for brain health, for fiber, for numerous reasons. However, it is about the type, the amount, and the quality of carbohydrates needed alongside protein and fat per individual that can make a significant difference,” Monique Richard emphasized.
The effectiveness of low-carbohydrate diets in reducing cardiovascular disease remains debatable. While some studies show favorable cholesterol outcomes, others argue that diets such as the Mediterranean diet, characterized by higher carbohydrate and lower fat intake, are associated with lower rates of cardiovascular disease.
“Usually low carbohydrate diets come with higher fat intake (and) that higher fat and cholesterol intake tends to lead to higher levels of cholesterol, so this finding would be a little bit unusual. I’d like to see it replicated in larger studies, but whether that actually leads to a reduction in cardiovascular disease is debatable, because we do know that generally higher carbohydrate, lower fat diets such as the Mediterranean diet tend to be a little bit more healthy and have lower rates of cardiovascular disease. My first reaction is definitely interesting and probably needs follow-up,” stated Yu-Ming Ni, MD.
The Iso and Hypo studies provide valuable insights into dietary management for individuals with type 2 diabetes. A key takeaway is the significance of personalized nutrition plans tailored to individual needs and responses to different foods.
“When educating my clients and patients on carbohydrates I let them know that ‘nothing is off the table’ (pun intended). It is all about understanding portion sizes as well as how that food acts in your body. One individual with diabetes may have a very different blood glucose reaction from pizza compared to another individual with diabetes,” Monique Richard explained.
The findings underscore the importance of ongoing research in determining optimal dietary strategies for managing type 2 diabetes and associated risks. As scientists continue to explore these areas, healthcare professionals can provide more informed guidance on nutritional choices.
“Often the first-line of addressing glucose control when working with those who have prediabetes or diabetes is adjusting carbohydrate intake as well as educating about why it matters (hint, carbohydrates break down to glucose which in turn affects blood glucose regulation), the quality, the variation among carbohydrate food groups (the carbohydrate profile of a donut is much different than the amount of carbohydrate in broccoli, or even a potato), and all the nuances in between,” added Monique Richard.
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