David J. Stensel, PhD
David J. Stensel, PhD, School of Sport and Exercise Sciences, Loughborough University, Loughborough, Leicestershire, United Kingdom.
Not that I advocate throwing caution to the wind… but if you absolutely must indulge in that big pasta dinner, make a point of taking a walk before or afterward. A new study conducted at Loughborough University in Leicestershire, United Kingdom, indicates that walking at a brisk pace for a half hour may be just what you need to offset the carbohydrate kick to your cholesterol profile.
The study examined whether daily exercise can reduce triglycerides in the blood, which rise along with the dietary ratio of carbohydrates to fat. The research was motivated by a public health movement in the UK encouraging people to alter their diet from their current typical caloric intake of 40% fats, 45% carbohydrates and 15% protein… to 30% fats and 55% carbs, leaving the protein at the same 15% level. Reducing fat is good, of course, but the problem is, when the ratio of carbohydrates to fats in the diet goes up, it raises triglycerides (also called triacylglycerol or TAG), especially immediately following a meal. According to study coauthor David Stensel, PhD, senior lecturer in Sports and Exercise Sciences at Loughborough, “This may negate the claimed cholesterol-lowering benefits, since elevated triacylglycerol concentration after meals is a risk factor for heart disease.”
Researchers recruited 14 study participants (male and female) between the ages of 45 and 65 with no history of heart disease or metabolic disorder, who were not taking cholesterol medication. None engaged in regular vigorous exercise and the women were all post-menopausal.
Each subject rotated through three four-day trials of different diets: the standard UK diet… the new “recommended” UK diet… and the recommended UK diet plus daily exercise. During the “recommended diet plus exercise” phase, subjects made daily lab visits at their own convenience for a 30-minute walk on a treadmill at a self-selected brisk pace (averaging about four miles per hour). The other phases did not include any exercise, beyond that inherent in daily living activities. On the last day of each phase, all subjects came to the laboratory and spent a day resting, eating meals of the type they were assigned at the time, and having periodic measurements taken of their resting respiration and metabolism and blood samples drawn to assess overall impact on cholesterol and TAG levels.
As expected, TAG concentrations did rise after meals for both phases with the changed diet, but especially in connection with the higher carbohydrate diet. The good news was adding exercise offset the carbohydrate-linked rise in TAG levels.
It is ironic that a diet that is better for you because of the lower proportion of fats can also pose a problem, says Dr. Stensel. But this study shows that 30 minutes of brisk walking every day can fix the problem of the higher TAG levels typically associated with added carbohydrates. So if you are going to eat those carbs, make it a point to step up that stroll.