Beware of Keto/Paleo/Whole 30 for Tennis Players!
By Page Love, MS, RDN, CSSD, LD
Yes, you’ve seen the ads and the media attention – not to mention headlines such as “Pasta Makes You Fat.” Fad diets like Ketogenic, Paleo and Whole 30 are characterized by high meat and fat intakes, and limited amounts of complex carbohydrate sources such as grains (bread, cereals,
Tennis players and other athletes must have muscle energy levels high enough to allow them to endure lengthy matches; sometimes two or three matches in one day! Fatigue and dehydration risks will quickly ensue if you fall prey to the latest fads of eliminating carbohydrates or fuel sources for tennis play.
For as long as we have been looking for a magic bullet to improve athletic performance, low-carbohydrate diets have been tempting the public. In the late 1920s and early 1930s, the Ketogenic diet was developed as a treatment option for epilepsy disorders, but it has since morphed into a diet trend. The demand to diet is ever-present and will continue to be for as long as the American media and public emphasize the necessity to look thin and lean at any cost. As a sport dietitian who works with both competitive juniors and professional players, I rarely see a player who will try or stay on these types of diets for long because of the numerous negative performance and health side effects listed below:
So, why beware? Here is a list of the top ten reasons not to fall prey to the high-protein, low-carbohydrate diets and the negative impact they may have on your tennis play and your health:
1. Low energy side effects
These diets purport low energy intakes, far below recommended intakes for the athletic population. For healthy weight loss, it is recommended to not only meet your basal metabolic needs, but also to eat adequately to eradicate the risk of organ deterioration and muscle wasting. A low-energy intake can jeopardize muscle energy levels, lead to earlier fatigue and be the difference between energy needed to make it through three versus two sets in the heat.
2. Higher protein intakes than needed
These diets have two to three times the recommended dietary intake for protein. This can put the body at increased risk for undue kidney stress, including nephrolithiasis (kidney stones), urinary tract infections and long-term kidney failure. For athletes, this can lead to increased complications of maintaining a normal hydration status as well as increased risk for heat stress.
3. Low antioxidant intake
These diets are so limited in antioxidant food variety that you cannot meet your recommended dietary allowances for key antioxidant vitamin and minerals without supplementation. Specifically, low fruit intake leads to inadequate Vitamin C for the body, potentially causing a suppressed immune system, which can increase your risk to illness and infection. This is detrimental for an athlete, instigating slower healing and increased risk of injury.
4. Dehydration side effects
These types of diets can lead to extreme water loss. Uric acid can build up due to excessive protein intake. The body eliminates the uric acid by flushing the body out with water. This, in turn, leads to an increased risk for dehydration, causing light-headedness, fatigue and decreased metabolic rates. All of these would negatively affect tennis performance.
5. Carbohydrates don’t cause weight gain/obesity
Most of these types of diets claim that high carbohydrate intakes are the cause of America’s problem with obesity. The scientific evidence does not support this theory as of yet. Carbohydrates are the body’s preferred fuel source for organ and brain function as well as for most physical activity. The body will store excess carbs as fat only when that excess is above the daily caloric expenditure needs for that individual.
6. Slow metabolism
Most of these diets are so low in carbohydrate intake that you do not receive adequate energy to keep your metabolism normalized. Over time, a person on a low-calorie, high-protein diet will slow his or her metabolism so severely that normal eating can cause immediate water gain, as the body tries to establish a normal balance again. For the tennis player, this can mean chronic fatigue feelings and trouble thermoregulating the body’s temperature.
7. Low healthy fiber intake
These diets are so low in fiber that your gut microbiota and function can be compromised. Complex carbohydrate fibers found in wheat bran and legume fibers are “pre-biotics.” A diet low in fiber has an increased risk for constipation, bloating and slowed gastric motility. This can increase your risk for colon diseases if you follow such diets chronically.
8. Can raise your cholesterol
These diets recommend excessive amounts of animal protein (>10 oz./day). This exorbitant intake will be accompanied with increased cholesterol and saturated fat intake well above the daily-recommended levels. Over time, this will raise blood lipid profiles. This kind of excess can put athletes at increased risk for heart and other inflammatory diseases.
9. Can lower bone density
Most of these diets have a detrimental side effect secondary to the diuretic response of flushing out of high protein diet metabolites. Because of the water loss, essential vitamins and minerals are lost from the body, especially calcium. Over time, the high intake of protein can cause a loss of calcium, which can lead to lower bone density and an increased risk of osteoporosis. For tennis players, this increases the risk of bone-related injuries such as stress fractures.
10. Long term may not help keep weight off
If your goal is to lose weight in the New Year, research does not support that these types of diets are successful with long-term weight loss. Some studies show that these diets will cause gradual weight gain about six months after following these types of diets. Most people who try these approaches will regain the initial weight they lost and then some.
High-protein diets are just another fad. Unfortunately, they can lead to a host of medical and performance complications for the tennis player. Trust eating plans that are nutritionally adequate, provide a well-balanced approach with acceptable carbohydrates for performance, as recommended by MyPlate and the 2015-2020 Dietary Guidelines and current
Page Love consults with both the WTA and ATP tennis tours and is on the USTA