Could Saturated Fats Be Less Harmful Than Previously Thought?
New research suggests that saturated fats might not be as detrimental to heart and overall health as previously believed.
Hypothesizing that consuming energy primarily from carbohydrate or fat in diets with similar food profiles would differentially affect the ability to reverse visceral adiposity and metabolic syndrome, researchers conducted a study of 46 men between the ages of 30 and 50, with body mass index greater than 20 and a waist circumference greater than 98 cm. Participants were randomly assigned to a very high-fat, low carbohydrate (VHFLC) diet or low-fat, high-carbohydrate (LFHC) diet for 12 weeks. The diets were equal in energy, protein, and food profile, emphasizing low-processed, lower-glycemic foods. Fat mass was quantified with computed tomography imaging.
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Recorded intake of carbohydrate and total and saturated fat in the LFHC and VHFLC groups were 51% and 11% of energy, 29% and 71% of energy, and 12% and 34% of energy, respectively, with no difference in protein and polyunsaturated fatty acids. Mean energy intake decreased by 22% and 14% in the LFHC and VHFLC groups, according to the authors, who note that the diets similarly reduced waist circumference, abdominal subcutaneous fat mass, visceral fat mass, and total body weight.
Both groups improved dyslipidemia, with reduced circulating triglycerides, but showed differential responses in total and low-density lipoprotein cholesterol (decreased in LFHC group only), and high-density lipoprotein cholesterol (increased in VHFLC group only). The groups showed similar reductions in insulin, insulin C-peptide, glycated hemoglobin, and homeostasis model assessment of insulin resistance.
The results “suggest that qualitative improvements to the diet are more important than choosing fats or carbohydrates as the primary energy source,” said Simon Nitter Dankel, an associate professor in the department of clinical science at the University of Bergen, and a co-author of the study.
Given such findings, primary care practitioners “first need to recognize the key importance of nutritional quality in obesity, diabetes, heart disease, and cancer,” he continued, noting that he and his co-authors found “great health benefits” by improving dietary quality, without a marked reduction in energy intake.
“Even our high-carbohydrate, low-fat group ate more saturated fats than recommended in official dietary guidelines,” said Dankel, adding that these participants still showed a substantial reduction in LDL cholesterol levels.
“Before the diets, our participants got around 15% [of their] energy from saturated fats,” he continued, noting that participants in the very high-fat group got 34% of their energy from saturated fats, but did not significantly increase LDL cholesterol after 3 months on the diet. Our study therefore suggests that small adjustments to saturated fat intake do not make a big difference for disease risk, and that a better strategy is to help people replace highly processed foods with whole foods and meals made from scratch.”
Veum VL, Laupsa-Borge J, Eng Ø, et al. Visceral adiposity and metabolic syndrome after very high–fat and low-fat isocaloric diets: a randomized controlled trial [published online November 30, 2016]. Am J Clin Nutr. doi:10.3945/ajcn.115.123463.