When it comes to nutrition, there are endless discussions about which macronutrients you should be eating the most or the least. There is always discussion about low-carb, low-fat, high-fat, and high-protein diets. But if we look at the evidence, we consistently find that a plant-based whole food diet is ideal for our overall health.
When we look at the evidence, we find that people who consume a predominantly Whole Foods plant-based diet have lower blood pressures by about five points than those who eat a predominantly meat-based diet. Even if you look at the risk of heart disease, for example, people who follow a Whole Foods plant-based diet have a 16 percent lower risk of developing heart disease, and their risk of dying from heart disease is lower by 31 percent. Even the risk of memory decline and dementia decreases by 20 percent with a plant-based diet. It actually doesn’t take much fruit and vegetable consumption. As little as 100 grams (3.5 ounces) per day reduces the risk of cognitive decline and dementia by 13 percent.
Let’s move away from health and look at weight loss. Can a low-fat whole-food plant-based diet help with weight loss? Let’s look at what the evidence shows. Here is a recent 16-week randomized clinical trial addressing this exact issue. The study included 244 participants with an age range of 25 to 80 years old and a BMI ranging between 28 to 40.
The study randomized the participants into two groups. The first group served as the control and received no dietary changes. The second group was given instructions on a low-fat, vegan diet consisting of 75% carbohydrates, 15% protein, and 10% fat. So what did they find? Here’s where it becomes really interesting.
Over the 16 week study period, the vegan arm lost 14 pounds while the control arm lost 1 lb. That is quite an impressive weight loss. Keep in mind, this was with diet alone, no medications or weight loss surgery. Looking at the data, we see that the vegan group had a calorie reduction of 354 kcal/day vs the control arm, which had a reduction of 135.8 kcal/d. However, this caloric deficit alone is not enough to account for the marked weight loss.
The vegan group had another significant change in their eating. Their fiber intake increased by 11.1 grams/day versus a 0.56 grams/day decrease in the control group. Keep in mind the average American fiber intake is only about 15 grams/day versus the recommended 30 grams per day.
Looking at insulin, the researchers found that the low-fat vegan group had a 21.6 pmol/L decrease in fasting plasma insulin vs no change in the control group. This was despite the large increase in carbohydrate intake compared to the control arm. The low-fat vegan arm also had a significant reduction in the insulin resistance index called HOMA (Homeostasis model assessment index) while the control arm had a small increase.
Thermic Effect of Food
The thermic effect of food (TEF) is defined as the energy needed to break down and absorb food. Generally speaking, the energy expended depends on the type of food consumed. With carbohydrates, about 5 to 15% of the energy consumed is used for (TEF) while for protein the TEF is closer to 20 to 35% of the energy.
In the study, the authors found that TEF increased by 18.7% in the vegan group and no significant change in the control group.
Lastly, the researchers looked at liver and muscle fat. This was tested on only 44 of the participants. In the low-fat vegan arm. liver fat decreased by 34.4% and remained unchanged for the control group. Interestingly, the change in liver fat was strongly linked with their change in body weight. Muscle fat was tested but was not found to be statistically significant between the 2 groups.
n fact, if anything, the liver fat actually increased a little bit. But in the treatment arm, in the Whole Foods plant based on the liver fat went down and it went down significantly. Same thing when they looked at the fat inside the muscles, what they saw was that in the low fat Whole Foods diet arm, the amount of fat inside the muscles actually went down.
What this randomized clinical trial shows is that in addition to supporting blood pressure, heart, brain, kidney, gastrointestinal health, a low-fat, whole-foods plant-based diet can also help with weight loss, fatty liver, and insulin resistance. There is one important caveat to remember, when we talk of carbohydrates, we are not talking about refined carbohydrates. Instead, we are referring to complex carbohydrates such as beans, oatmeal, whole wheat bread, quinoa, barley, potatoes, and sweet potatoes.