- A
ketogenic (keto) diet outperformed a Mediterranean diet in improving
metabolic health metrics in a new, very small study in people who had
recently received a diabetes diagnosis.
- The
study found that a keto diet improved blood sugar, gut microbiota
composition, body mass index (BMI), and waist circumference more than a
Mediterranean diet.
- The
keto diet has proven to be successful for weight loss, but has been
associated with numerous adverse effects. It involves a radical reduction
in carbohydrates, and changes the way the body accesses energy.
- The
advantages the keto diet exhibited over the Mediterranean diet were not
long-lasting in the year-long study, fading after 6 months.
Compared to a
Mediterranean diet, a ketogenic (keto) diet produced more immediate beneficial
changes in people with type 2 diabetes during a 12-month study.
However, the keto diet’s
relative advantages appeared to wane beyond 6 months. The diets resulted in
similar improvements in participants’ health by the end of the study.
The small study, conducted by researchers in Italy
and Brazil, and whose findings appeared in the journal Metabolites, recorded short-term
improvements in gut microbial diversity, various anthropometric measures, and
metabolic indicators.
The keto diet is a
weight-loss diet based on the principle that by dramatically limiting the
presence of carbohydrates (sugars)
available to the body, the body will instead burn away fat for energy. The diet
can produce significant weight loss and has been linked to other benefits.
However, the keto diet
has also been associated with various serious adverse effects, especially with
long-term use, making it difficult to safely study in human subjects.
The Mediterranean diet takes
a less radical approach to dieting, emphasizing a balanced approach to
nutrition and lifestyle.
Participants in the
study were people aged 45 to 65 with obesity who had recently been received
a type 2
diabetes diagnosis.
They had not yet begun
taking any medication for the condition. At the start of the study, there were
11 participants. By the halfway point, 10 remained, and eight people completed
the full year-long trial.
The individuals had been
randomly assigned either to a very low-calorie ketogenic diet or to a
Mediterranean-type diet. Those in the low-calorie keto group were supplied
protein-based meals containing few carbohydrates — less than 30 grams (g) per
day.
After 2 months, people in the low-calorie keto group
were gradually transitioned to the Mediterranean diet to avoid keto-diet safety
issues.
From month 4 onward,
both groups followed an Mediterranean diet for the remainder of the study.
Metabolic
benefits: How was keto better than a Mediterranean diet?
At the start of the
study and throughout the year, the researchers took stool samples from
participants and used next-generation genetic sequencing to identify the
microbiota they contained.
They also took
anthropometric measurements — such as body mass index (BMI) and waist
circumference — and measured key metabolic values such as hemoglobin A1C (HbA1c),
a key indicator of blood sugar, and triglycerides,
a marker of cholesterol.
At month 6, those in the low-calorie
keto group exhibited significant improvements beyond the Mediterranean
diet group in HbA1c levels, BMI, waist circumference, and beneficial gut
bacteria.
Among the low-calorie
keto group’s enhanced gut bacteria was the Akkermansia species,
which is involved in metabolic health and gut barrier protection.
After 6 months, however,
most of these indicators of health improvement receded, though they never fell
back to where participants were at the start of the study, leaving the
researchers encouraged about keto.
What are the
concerns about keto diets?
“The keto diet can have
risks such as nutrient deficiencies, liver issues, constipation, and kidney
issues,” explained Jason
Ng, MD, BA, of the Department of Medicine at the University of Pittsburgh,
an expert in endocrinology and metabolism, explained to Medical News
Today.
“Nutrient deficiencies can occur from not eating a
variety of vegetables and grains that may have nutrients. Liver and kidney
issues can occur because of the high demand for metabolizing fat and proteins
that can overload those organs. Constipation occurs from not eating fibrous
foods that can keep bowel movements regular. Mood swings and difficulty
thinking can occur sometimes when your brain is deprived of sugar,” added Ng,
who was not involved in the current study.
Michelle Routhenstein,
MS, RD, CDCES, CDN, founder of, and preventive cardiology dietitian and
heart health expert at EntirelyNourished, also not involved in the current
research, also told MNT:
“In
my private practice, I frequently see patients who have tried the keto diet and
are dealing with increased blood sugar, inflammation, elevated blood pressure,
and worsening lipid profiles.”
A potential
role for the keto principle
Commenting on the
results of the study, Ng told us he remained cautious for the moment.
“Potential weight loss
and possible improvement in gut microbiota from keto diets may be possible in
carefully selected patients who are healthy otherwise, and with close
monitoring to ensure minimization of those side effects,” he noted.
For those with type 2
diabetes, in particular, he agreed that “a keto diet may be a valuable tool in
the management of obesity and improvement in insulin resistance in
patients […] who cannot lose weight or have variable sugar control.”
However, Routhenstein did not “ recommend a keto
diet for individuals with type 2 diabetes, as the condition already heightens
the risk of heart disease.”
Both framed a
Mediterranean diet as a safer bet.
“A Mediterranean diet,”
noted Ng, “is a valuable resource and tool to help people with [type 2
diabetes] control their sugars, improve weight loss, and is likely easier to
maintain than a keto diet, and is an established diet that can improve the
health of patients with [this conditon].”
“Rather than following
fad diets,” Routhenstein advised, “I recommend focusing on nutrient adequacy,
effective meal planning, and a balanced approach that includes proper timing
for meals. This strategy is more sustainable for managing type 2 diabetes and
improving overall health.”
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