Swedish researchers wondered if adding an exercise program to the Paleo diet in overweight type 2 diabetics would improve blood sugars or insulin sensitivity. Surprisingly, it did not. Exercise did, however, improve cardiovascular fitness.
How Was the Research Done?
Study participants in northern Sweden had been diagnosed with diabetes within the last 8 years and were either taking metformin (about 2/3 of them) or were using lifestyle modification (primarily diet, I presume) to treat diabetes. Folks on additional diabetes drugs were excluded. Baseline BMI was between 25 and 40, with and average of 31.5. (For example, a 5-ft, 9-inch person weighing 206 lb has a BMI of 30.4.) Men were 30–70 years old; women were post-menopausal or up to age 70 (no explanation given for excluding younger women). A third of participants were women. All were sedentary at the time of enrollment. Baseline hemoglobin A1c’s were between 6.5 and 10.8% (average of 7.2%).
Participants were divided into two groups (14 or 15 in each):
- Paleolithic diet (PD)
- Paleolithic diet plus thrice weekly supervised exercise (PD-EX)
The exercise regimen was included both aerobic and resistance training. Click the reference link below for details. It looks like a vigorous and reasonable program to me.
The study lasted for 12 weeks.
Here’s their Paleo diet: “…lean meat, fish, seafood, eggs, vegetables, fruits, berries, and nuts. Cereals, dairy products, legumes, refined fats, refined sugars, and salt were excluded with the exception of canned fish and cold cuts like ham. The diet was consumed ad libitum [i.e., they could eat as much as they wanted], with restrictions of the following: eggs (1–2/day but a maximum of 5/week, potatoes (1 medium sized/day), dried fruit (130 g/day), and nuts (60 g/day). Rapeseed or olive oil (maximum 15 g/day) and small amounts of honey and vinegar were allowed as flavoring in cooking. Participants were instructed to drink mainly still water. Coffee and tea were restricted to a maximum of 300 g/day, and red wine to a maximum of one glass/week.
What Did They Find?
- Both groups had and average individual weight loss of 7.1 kg (15.4 lb).
- Both groups lost fat mass (measured by DEXA). The males in the PD-EX group retained more lean mass (e.g., muscle) than the other males.
- Insulin sensitivity and blood sugar control improved in both groups to a comparable degree.
- Hemoglobin A1c dropped about 1% in both groups.
- VO2max (a measure of cardiovascular fitness) increased only in the PD-EX group, from 22.5 to 25.8 mL/kg/min.
- Both groups dropped both systolic and diastolic blood pressures by 10%.
- Both groups cut their leptin levels by about half. Leptin causes inflammation and is linked to cardiovascular events (heart attacks, strokes).
This study adds to the relatively few previous ones proving that the Paleo diet is effective in diabetes (overweight and obese type 2 diabetes in this case).
Fifteen-pound weight loss over 12 weeks while eating as much as you want is amazing.
The 1% absolute drop in Hemoglobin A1c is also quite welcome, comparable to or better than the reductions we see with many of our diabetes drugs. The authors remind us that “The UK prospective diabetes study (UKPDS) stated that a 1% unit improvement of HbA1c reduces microvascular complications by 37% and reduces diabetes-related death by 21%.”
The exercise program didn’t add to the weight loss. No surprise there. Unless you’re a contestant on The Biggest Loser show, 90% of weight loss depends on diet.
Unlike other studies, the exercisers didn’t see extra improvement in insulin resistance or blood sugar control. I can’t explain it.
The 10% blood pressure reduction by this Paleo diet could be quite beneficial for an individual with high blood pressure, allowing drug avoidance or dose reduction. Systolic pressure of 150 mmHg is often treated with drugs; a 10% reduction gets you down to 135, which doesn’t require drug therapy.
Note the 3.3 mL/kg/min increase in VO2max from this exercise program, which could be an 18% in all-cause mortality if sustained over time. The investigators cite a cohort study that found a VO2max increase of 1.44 mL/kg/min reduced overall mortality by 7.9%.
Reference: Otten, et al. (including Ryberg and Olsson). Effects of a Paleolithic diet with and without supervised exercise on fat mass, insulin sensitivity, and glycemic control: a randomized controlled trial in individuals with type 2 diabetes. Diabetes/Metabolism Research and Reviews, 2017; 33(1): doi: 10.1002/dmrr.2828 Published online in 2016.