New Study: Eat as much as you want and reverse insulin resistance by 50%?

Summary

The video reviews a 16-week study of a low-fat vegan diet in people with type 2 diabetes. Participants could eat freely—“ad libitum”—rather than follow a prescribed calorie limit. The presenter highlights improvements in insulin-resistance measures, blood sugar, body fat, liver fat, cholesterol, and an indicator of advanced glycation end products (AGEs).

Study and diet

• The study included 25 people, with an average age of about 65 and an average diabetes duration of roughly 6.5 years.
• Participants followed a low-fat vegan diet emphasizing whole plant foods. They increased carbohydrate intake, particularly from plant foods, while saturated-fat intake fell substantially.
• Participants were not instructed to restrict calories. However, their self-reported calorie intake fell by about 340 kcal per day, even as they reported eating more food by weight.
• The presenter suggests that fiber, food volume, and other properties of whole plant foods may increase fullness and affect GLP-1, but the video does not establish those mechanisms.

Reported results

• Insulin resistance: The reported score decreased from 5 to 2.5, a 50% reduction.
• Blood sugar: Average fasting glucose fell from 155 to 115. Average HbA1c fell from 7.6 to 6.6.
• Insulin response: The pancreas’s insulin secretion in response to glucose increased by more than 50%, which the presenter interprets as improved insulin sensitivity and beta-cell function.
• Body fat: Participants lost an average of 4.2 kg (over 9 lb) of fat and 290 cm³ of visceral fat, the fat around internal organs.
• Liver fat: It decreased by about one-third.
• Cholesterol: LDL cholesterol fell by 22 points, despite around 40% of participants already using cholesterol-lowering medication.
• Saturated fat: Intake decreased by about 75%.
• AGE indicator: Skin fluorescence, used as a measure related to AGEs, decreased by 15%. The presenter notes that this was statistically significant and that the measure reflects a relatively slow-changing tissue marker.

The presenter contrasts the findings with low-carbohydrate diets, arguing that participants increased carbohydrate intake from whole plant foods while their insulin-resistance score improved. That is the presenter’s interpretation; the study itself, as described in the video, does not directly compare the diet with a low-carbohydrate diet.

Limitations and interpretation

• This was a single-arm before-and-after study, with no control group. It can show that the measures changed during the study, but it cannot establish that the diet alone caused the changes as reliably as a controlled comparison could.
• The sample was small, and the intervention lasted four months.
• The presenter says the results resemble those from earlier randomized controlled trials of similar diets, though those trials did not measure as many of the markers discussed here.
• The video notes that an HbA1c of 6.5 is a common diagnostic threshold, but an average HbA1c of 6.6 does not by itself show how many individuals fell below that threshold or establish that diabetes was reversed.
• The study was funded by the Physicians Committee for Responsible Medicine (PCRM) and also received National Institutes of Health (NIH) grants. The presenter acknowledges PCRM’s association with the diet being studied and considers NIH funding a factor in the study’s credibility.

Speakers and sources featured

• Speaker: The video’s narrator/host, identified in the subtitles as Mike (the channel is Mic the Vegan).
• Researcher mentioned: Neil Barnard, associated with the study team and PCRM.
• Main source: A study published in BMJ Open Diabetes Research & Care.
• Funding sources mentioned: Physicians Committee for Responsible Medicine (PCRM) and the National Institutes of Health (NIH).
• Other sources or evidence referenced in passing: Prior research on GLP-1 and fiber, and an example of metformin’s effect on fasting glucose; no additional researchers are named in the subtitles.