Updated August 25, 2021
By John McDougall, MD
I meet people every week who are surprised and upset to find their cholesterol levels did not go down after they started an exercise program. This failure to lower cholesterol is even more astonishing when they hear claims from exercise enthusiasts that people who run marathons never have a heart attack – even though the cemeteries are filled with long distance runners who have died from this disease. The famous runner and author of The Complete Book of Running, Jim Fixx, is a telling example of a man who made this claim, yet met his end in 1984 from a heart attack at age 56. His arteries were plugged solid with atherosclerosis.
The truth is: physical activity and fitness will reduce your risk of cardiovascular disease (strokes and heart attacks). But the benefits fall far short of immunity and one reason may be that exercise shows no benefit on two of the most important risk factors for heart disease — total and LDL cholesterol.
The November 7, 2002 issue of the New England Journal of Medicine published the latest research showing no change in total or LDL cholesterol with exercise.1 However, there were some small changes in other less important risk factors. Of the risk factors commonly measured, triglycerides decreased with all levels of exercise by 20 to 60 mg/dl, and HDL increased by 4.8 mg/dl only with a large amount of high intensity exercise (equivalent to 20 miles a week of jogging). The subjects studied were overweight men and women, who were asked to eat enough during the study so they did not lose weight. Even without weight loss they showed these improvements in triglycerides and HDL levels, which are important.
Data published in the scientific literature consistently shows the benefits of the low-fat, no cholesterol, McDougall Diet, on blood cholesterol. With our program “It’s the Food” and a prescription for exercise is only a small part of the intervention and benefits. With little or no emphasis on increasing any kind of exercise we found a 22 mg/dl (0.6 IU) improvement in cholesterol in 7 days. Two independent long-term studies (12 months) showed a similar reduction in cholesterol level is maintained for an entire year. Eighty-five percent of people made permanent changes because of the dramatic positive improvements in their life and they loved the food. 2-4
Exercise has clear health benefits in addition to those mentioned above, like losing weight, lowering blood pressure, improving mood, strengthening bone, making appetite more appropriate, building muscles, improving insulin sensitivity and lowering blood sugars. Therefore, do not discount its importance because of the lack of cholesterol-lowering effects. However, most people who exercise are also interested in gaining longevity and excellent health. They need to understand that exercise is only one part of the equation for excellent health and that diet cannot be ignored. Furthermore, I think it is important for people who plan to start an exercise program to get their diet fixed first.5
Starting an intensive exercise program while in poor health could be a prescription for trouble – even the possibility of precipitating a heart attack with the intense exercise.5-7 This tragedy can occur because heavy exercise may cause the disruption of a volatile plaque in one of the heart arteries, resulting in complete closure of the artery – and death of the heart muscle (a heart attack). Eating a healthy diet for a period of time before the intense exercise will help stabilize the plaque and prevent its rupture (See the McDougall Program for a Healthy Heart book.)
I encourage you to start a regular exercise program, but start it slowly and build your exercise up at a comfortable pace. You can usually tell if you are overexerting when you have difficulty talking at the same time you exercise. Along with your exercise, start a low-fat, pure vegetarian diet now and you will be on the road to excellent health.
Update of studies on exercise and cholesterol (2021): Research over the past 20 years has confirmed the lack of benefits of various kinds of exercise on blood cholesterol levels. Comparing aerobic exercise with resistance exercise there is no difference in the control of glycemic (blood sugar) and lipid levels (cholesterol, LDL cholesterol, and HDL-cholesterol) between the two types of exercise, according to an analysis of multiple studies published in 2017 (a meta-analysis).8 Any benefits from exercise are indirect and a consequence weight loss and lowering of triglycerides (blood fats).9
1) Kraus WE. Effects of the amount and intensity of exercise on plasma lipoproteins. N Engl J Med.2002 Nov 7;347(19):1483-92.
2) McDougall J. Effects of 7 days on an ad libitum low-fat vegan diet: the McDougall Program cohort. Nutr J 13, 99 (2014).
3) Yadav V. Low-fat, plant-based diet in multiple sclerosis: A randomized controlled trial. Multiple Sclerosis and Related Disorders 9 (2016) 80–90.
4) Wright N. The BROAD study: A randomised controlled trial using a whole food plant-based diet in the community for obesity, ischaemic heart disease or diabetes. Nutr & Diabetes 7, e256 (2017).
5) Mittleman MA, Maclure M, Tofler GH, Sherwood JB, Goldberg RJ, Muller JE. Triggering of acute myocardial infarction by heavy physical exertion — protection against triggering by regular exertion. N Engl J Med 1993;329:1677-1683.
6) Willich SN, Lewis M, Lowel H, Arntz H-R, Schubert F, Schroder R. Physical exertion as a trigger of acute myocardial infarction. N Engl J Med 1993;329:1684-1690.
7) Curfman GD. Is exercise beneficial — or hazardous — to your heart? N Engl J Med 1993;329:1730-1731.
8) Cybelle N. Effectiveness of resistance exercise compared to aerobic exercise without insulin therapy in patients with type 2 diabetes mellitus: a meta-analysis. Braz J Phys Ther. 2017 Nov-Dec; 21(6):400-415.)
9) Clifton P. Diet, exercise and weight loss and dyslipidaemia. Pathology. 2019 Feb;51(2):222-226.