The effects of varying dietary fat on the nutrient intake in male and female runners

Nutrient Adequacy in Endurance Athletes

Proper nutrition is critical for optimal performance in endurance athletes. However, it is unclear if endurance athletes are meeting all their energy and nutrient needs. We examined if endurance athletes are meeting their nutritional requirements and if this differed by sex. Ninety-five endurance athletes (n = 95; 50.5% men; 34.9 ± 12.9 y) participated in the study. Dietary intake was evaluated using the 24 h dietary recall method. Energy and nutrient intakes were calculated using the ESHA Food Processor Diet Analysis Software and compared against reference nutrient intakes. Endurance athletes did not consume the recommended amount of energy (76.8% of athletes), carbohydrates (95.8%), linoleic acid (75.8%), α-linolenic acid (ALA) (77.9%), eicosatetraenoic and docosahexaenoic acid (96.8%), dietary fiber (49.5%), vitamins D (93.7%), E (71.6%), and K (54.7%), folate (54.7%), pantothenic acid (70.5%), biotin (83.2%), manganese (58.9%), magnesium (56.8%), chromium (91.6%), molybdenum (93.7%), choline (85.3%), and potassium (56.8%), and consumed too much saturated fat (50.5%) and sodium (94.7%) than recommended. Fisher's Exact test showed that the requirements for dietary fiber (70.8% vs. 27.7%), ALA (87.5% vs. 68.1%), and total water (70.8% vs. 44.7%) were not met by more men versus women (p < 0.05). The needs for protein (70.2% vs. 25%) and vitamin B12 (46.8% vs. 22.9%) were not met by more women compared to men (p < 0.05). These findings need to be confirmed by a larger study.

Nutrition and Physical Activity in British Army Officer Cadet Training Part 2-Daily Distribution of Energy and Macronutrient Intake

Dietary intake and physical activity impact performance and adaptation during training. The aims of this study were to compare energy and macronutrient intake during British Army Officer Cadet training with dietary guidelines and describe daily distribution of energy and macronutrient intake and estimated energy expenditure. Thirteen participants (seven women) were monitored during three discrete periods of military training for 9 days on-camp, 5 days of field exercise, and 9 days of a mixture of the two. Dietary intake was measured using researcher-led food weighing and food diaries, and energy expenditure was estimated from wrist-worn accelerometers. Energy intake was below guidelines for men (4,600 kcal/day) and women (3,500 kcal/day) during on-camp training (men = -16% and women = -9%), field exercise (men = -33% and women = -42%), and combined camp and field training (men and women both -34%). Carbohydrate intake of men and women were below guidelines (6 g·kg-1·day-1) during field exercise (men = -18% and women = -37%) and combined camp and field training (men = -33% and women = -39%), respectively. Protein intake was above guidelines (1.2 kcal·kg-1·day-1) for men and women during on-camp training (men = 48% and women = 39%) and was below guidelines during field exercise for women only (-27%). Energy and macronutrient intake during on-camp training centered around mealtimes with a discernible sleep/wake cycle for energy expenditure. During field exercise, energy and macronutrient intake were individually variable, and energy expenditure was high throughout the day and night. These findings could be used to inform evidenced-based interventions to change the amount and timing of energy and macronutrient intake around physical activity to optimize performance and adaptations during military training.

Nutritional optimization for female elite football players-topical review

Women's football is an intermittent sport characterized by frequent intense actions throughout the match. The high number of matches with limited recovery time played across a long competitive season underlines the importance of nutritional strategies to meet these large physical demands. In order to maximize sport performance and maintain good health, energy intake must be optimal. However, a considerable proportion of female elite football players does not have sufficient energy intake to match the energy expenditure, resulting in low energy availability that might have detrimental physiologic consequences and impair performance. Carbohydrates appear to be the primary fuel covering the total energy supply during match-play, and female elite football players should aim to consume sufficient carbohydrates to meet the requirements of their training program and to optimize the replenishment of muscle glycogen stores between training bouts and matches. However, several macro- and micronutrients are important for ensuring sufficient energy and nutrients for performance optimization and for overall health status in female elite football players. The inadequacy of macro-and micronutrients in the diet of these athletes may impair performance and training adaptations, and increase the risk of health disorders, compromising the player's professional career. In this topical review, we present knowledge and relevant nutritional recommendations for elite female football players for the benefit of sports nutritionists, dietitians, sports scientists, healthcare specialists, and applied researchers. We focus on dietary intake and cover the most pertinent topics in sports nutrition for the relevant physical demands in female elite football players as follows: energy intake, macronutrient and micronutrient requirements and optimal composition of the everyday diet, nutritional and hydration strategies to optimize performance and recovery, potential ergogenic effects of authorized relevant supplements, and future research considerations.

Recommendations and Nutritional Considerations for Female Athletes: Health and Performance

Optimal nutrition is an important aspect of an athlete’s preparation to achieve optimal health and performance. While general concepts about micro- and macronutrients and timing of food and fluids are addressed in sports science, rarely are the specific effects of women’s physiology on energy and fluid needs highly considered in research or clinical practice. Women differ from men not only in size, but in body composition and hormonal milieu, and also differ from one another. Their monthly hormonal cycles, with fluctuations in estrogen and progesterone, have varying effects on metabolism and fluid retention. Such cycles can change from month to month, can be suppressed with exogenous hormones, and may even be manipulated to capitalize on ideal timing for performance. But before such physiology can be manipulated, its relationship with nutrition and performance must be understood. This review will address general concepts regarding substrate metabolism in women versus men, common menstrual patterns of female athletes, nutrient and hydration needs during different phases of the menstrual cycle, and health and performance issues related to menstrual cycle disruption. We will discuss up-to-date recommendations for fueling female athletes, describe areas that require further exploration, and address methodological considerations to inform future work in this important area.

The Mediterranean dietary pattern for optimising health and performance in competitive athletes: a narrative review

Nutrition plays a key role in training for, and competing in, competitive sport, and is essential for reducing risk of injury and illness, recovering and adapting between bouts of activity, and enhancing performance. Consumption of a Mediterranean diet (MedDiet) has been demonstrated to reduce risk of various non-communicable diseases and increase longevity. Following the key principles of a MedDiet could also represent a useful framework for good nutrition in competitive athletes under most circumstances, with potential benefits for health and performance parameters. In this review, we discuss the potential effects of a MedDiet, or individual foods and compounds readily available in this dietary pattern, on oxidative stress and inflammation, injury and illness risk, vascular and cognitive function, and exercise performance in competitive athletes. We also highlight potential modifications which could be made to the MedDiet (whilst otherwise adhering to the key principles of this dietary pattern) in accordance with contemporary sports nutrition practices, to maximise health and performance effects. In addition, we discuss potential directions for future research.

Dietary Fuels in Athletic Performance

Focusing on daily nutrition is important for athletes to perform and adapt optimally to exercise training. The major roles of an athlete's daily diet are to supply the substrates needed to cover the energy demands for exercise, to ensure quick recovery between exercise bouts, to optimize adaptations to exercise training, and to stay healthy. The major energy substrates for exercising skeletal muscles are carbohydrate and fat stores. Optimizing the timing and type of energy intake and the amount of dietary macronutrients is essential to ensure peak training and competition performance, and these strategies play important roles in modulating skeletal muscle adaptations to endurance and resistance training. In this review, recent advances in nutritional strategies designed to optimize exercise-induced adaptations in skeletal muscle are discussed, with an emphasis on mechanistic approaches, by describing the physiological mechanisms that provide the basis for different nutrition regimens.

Influence of exercise on nutritional requirements

There is no consensus on the best diet for exercise, as many variables influence it. We propose an approach that is based on the total energy expenditure of exercise and the specific macro- and micronutrients used. di Prampero quantified the impact of intensity and duration on the energy cost of exercise. This can be used to determine the total energy needs and the balance of fats and carbohydrates (CHO). There are metabolic differences between sedentary and trained persons, thus the total energy intake to prevent overfeeding of sedentary persons and underfeeding athletes is important. During submaximal sustained exercise, fat oxidation (FO) plays an important role. This role is diminished and CHO's role increases as exercise intensity increases. At super-maximal exercise intensities, anaerobic glycolysis dominates. In the case of protein and micronutrients, specific recommendations are required. We propose that for submaximal exercise, the balance of CHO and fat favors fat for longer exercise and CHO for shorter exercise, while always maintaining the minimal requirements of each (CHO: 40% and fat: 30%). A case for higher protein (above 15%) as well as creatine supplementation for resistance exercise has been proposed. One may also consider increasing bicarbonate intake for exercise that relies on anaerobic glycolysis, whereas there appears to be little support for antioxidant supplementation. Insuring minimal levels of substrate will prevent exercise intolerance, while increasing some components may increase exercise tolerance.

Effect of dietary fat on serum and intramyocellular lipids and running performance

PURPOSE

This study evaluated whether lowering IMCL stores via 3-d consumption of very-low-fat (LFAT) diet impairs endurance performance relative to a moderate-fat diet (MFAT), and whether such a diet unfavorably alters lipid profiles.

METHODS

Twenty-one male and female endurance-trained runners followed a controlled diet and training regimen for 3 d prior to consuming either a LFAT (10% fat) or MFAT (35% fat) isoenergetic diet for another 3 d in random crossover fashion. On day 7, runners followed a glycogen normalization protocol (to equalize glycogen stores) and then underwent performance testing (90-min preload run at 62 +/- 1% VO2max followed by a 10-km time trial) on the morning of day 8. Muscle biopsies obtained from vastus lateralis before and after performance testing were analyzed for IMCL (via electron microscopy) and glycogen content (via enzymatic methodology).

RESULTS

Despite approximately 30% lower IMCL (0.220 +/- 0.032% LFAT, 0.316 +/- 0.049% MFAT; P = 0.045) and approximately 22% higher muscle glycogen stores at the start of performance testing (P = 0.10), 10-km performance time was not significantly different following the two diet treatments (43.5 +/- 1.4 min LFAT vs 43.7 +/- 1.2 min MFAT). However, LFAT produced less favorable lipid profiles (P < 0.01) by increasing fasting triglycerides (baseline = 84.9 +/- 8.6; LFAT = 118.7 +/- 10.0 mg.dL(-1)) and the total cholesterol:HDL cholesterol ratio (baseline = 3.42 +/- 0.13:1; LFAT = 3.75 +/- 0.20:1), whereas MFAT lowered triglycerides (baseline = 97.5 +/- 12.2; MFAT = 70.9 +/- 7.1 mg.dL(-1)) and the total cholesterol:HDL cholesterol ratio (baseline = 3.47 +/- 0.18:1; MFAT = 3.33 +/- 0.14:1).

CONCLUSION

The results suggest that reducing IMCL via 3-d consumption of a LFAT diet does not impair running performance lasting a little over 2 h (compared with 3-d consumption of a MFAT diet plus 1-d glycogen normalization), but that even short-term consumption of a LFAT diet may unfavorably alter serum lipids, even in healthy, endurance-trained runners.

Fat intake and injury in female runners

BACKGROUND

Our purpose was to determine the relationship between energy intake, energy availability, dietary fat and lower extremity injury in adult female runners. We hypothesized that runners who develop overuse running-related injuries have lower energy intakes, lower energy availability and lower fat intake compared to non-injured runners.

METHODS

Eighty-six female subjects, running a minimum of 20 miles/week, completed a food frequency questionnaire and informed us about injury incidence over the next year.

RESULTS

Injured runners had significantly lower intakes of total fat (63 +/- 20 vs. 80 +/- 50 g/d) and percentage of kilocalories from fat (27 +/- 5 vs. 30 +/- 8 %) compared with non-injured runners. A logistic regression analysis found that fat intake was the best dietary predictor, correctly identifying 64% of future injuries. Lower energy intake and lower energy availability approached, but did not reach, a significant association with overuse injury in this study.

CONCLUSION

Fat intake is likely associated with injury risk in female runners. By documenting these associations, better strategies can be developed to reduce running injuries in women.

The Female Athlete Triad

The female athlete triad (Triad) refers to the interrelationships among energy availability, menstrual function, and bone mineral density, which may have clinical manifestations including eating disorders, functional hypothalamic amenorrhea, and osteoporosis. With proper nutrition, these same relationships promote robust health. Athletes are distributed along a spectrum between health and disease, and those at the pathological end may not exhibit all these clinical conditions simultaneously. Energy availability is defined as dietary energy intake minus exercise energy expenditure. Low energy availability appears to be the factor that impairs reproductive and skeletal health in the Triad, and it may be inadvertent, intentional, or psychopathological. Most effects appear to occur below an energy availability of 30 kcal.kg(-1) of fat-free mass per day. Restrictive eating behaviors practiced by girls and women in sports or physical activities that emphasize leanness are of special concern. For prevention and early intervention, education of athletes, parents, coaches, trainers, judges, and administrators is a priority. Athletes should be assessed for the Triad at the preparticipation physical and/or annual health screening exam, and whenever an athlete presents with any of the Triad's clinical conditions. Sport administrators should also consider rule changes to discourage unhealthy weight loss practices. A multidisciplinary treatment team should include a physician or other health-care professional, a registered dietitian, and, for athletes with eating disorders, a mental health practitioner. Additional valuable team members may include a certified athletic trainer, an exercise physiologist, and the athlete's coach, parents and other family members. The first aim of treatment for any Triad component is to increase energy availability by increasing energy intake and/or reducing exercise energy expenditure. Nutrition counseling and monitoring are sufficient interventions for many athletes, but eating disorders warrant psychotherapy. Athletes with eating disorders should be required to meet established criteria to continue exercising, and their training and competition may need to be modified. No pharmacological agent adequately restores bone loss or corrects metabolic abnormalities that impair health and performance in athletes with functional hypothalamic amenorrhea.

Low Energy Availability in the Marathon and Other Endurance Sports

Energy availability is the amount of dietary energy remaining after exercise training for all other metabolic processes. Excessively low energy availability impairs reproductive and skeletal health, although genetics and age may alter an individual's initial conditions and sensitivity when low energy availability is imposed. Many marathon runners and other endurance athletes reduce energy availability either (i) intentionally to modify body size and composition for improving performance; (ii) compulsively in a psychopathological pattern of disordered eating; or (iii) inadvertently because there is no strong biological drive to match energy intake to activity-induced energy expenditure. Inadvertent low energy availability is more extreme when consuming a low fat, high carbohydrate diet. Low energy availability, reproductive disorders, low bone mineral density and stress fractures are more common in female than male athletes. Functional menstrual disorders caused by low energy availability should be diagnosed by excluding diseases that also disrupt menstrual cycles. To determine energy availability (in units of kilocalories or kilojoules per kilogram of fat-free mass), athletes can record their diets and use diet analysis software to calculate energy intake, measure energy expenditure during exercise using a heart monitor and measure fat-free mass using a bioelectrical impedance body composition scale. All are commercially available at consumer prices.

Exercise and the Institute of Medicine Recommendations for Nutrition

The Food and Nutrition Board of the Institutes of Medicine (IOM) recently released energy, macronutrient, and fluid recommendations, which acknowledged for the first time that active individuals have unique nutritional needs. The IOM calculated an acceptable macronutrient distribution range for carbohydrate (45%-65% of energy), protein (10%-35% of energy), and fat (20%-35% of energy; limit saturated and trans fats). These proportions provide a range broad enough to cover the macronutrient needs of most active individuals, but specific carbohydrate and protein recommendations are also typically made based on a g/kg body weight formula. These ranges are 5 to 12 g of carbohydrate/kg body weight and 1.2 to 1.8 g/kg body weight for protein depending on the level of physical activity. The IOM report also gives recommendations for the two essential fatty acids: linoleic acid (men, 14-17 g/d; women, 11-12 g/d) and linolenic acid (men, 1.6 g/d; women, 1.1 g/d). Baseline adequate intakes for fluid (water + other beverages) were set at 3.0 L and 2.2 L for sedentary men and women, respectively, with higher intakes needed to account for physical activity and exposure to extreme environments.

Effect of low and high fat diets on nutrient intakes and selected cardiovascular risk factors in sedentary men and women

OBJECTIVE

The desired level of dietary fat intake is controversial. The effect of decreasing fat intake to 19% and increasing it to 50% from a control diet of 30% on nutritional status and cardiovascular risk factors in healthy individuals was studied.

METHODS

Eleven healthy subjects (5 men and 6 women) were randomized to consume diets with 19% and 50% calories from fat. Each diet lasted 3 weeks, with a one-week washout. The habitual and washout diets were determined to be 30% fat. At the beginning and the end of each diet, fasting blood was collected to determine plasma lipoproteins, and physiological factors were measured.

RESULTS

Total caloric expenditure was similarly balanced to intake on the 30% and 50% fat diets, but intake was significantly lower on the 19% fat diet and led to a loss of 0.6 kg body weight. Consumptions of essential fatty acids, vitamin E and zinc were improved with increased fat intake, but folate intake was compromised on the 30% and 50% fat diets. Compared with the 50% fat diet, subjects consuming the 19% fat diet had significantly lower HDL cholesterol (HDL-C) (54 +/- 3 vs. 63 +/- 3 mg. dL(-1), p < 0.05) and apolipoprotein A1 (ApoA1) (118 +/- 4 vs. 127 +/- 3 mg/dL, p < 0.05). Changing the levels of fat intake did not affect % body fat, heart rate, blood pressure, blood triglycerides, total cholesterol (TC), LDL cholesterol, apolipoprotein B (ApoB), TC/HDL-C and ApoA1/ApoB ratios.

CONCLUSION

A low fat diet (19%) may not provide sufficient calories, essential fatty acids, and some micronutrients (especially vitamin E and zinc) for healthy untrained individuals, and it also lowered ApoA1 and HDL-C. Increasing fat intake to 50% of calories improved nutritional status, and did not negatively affect certain cardiovascular risk factors.

Effect of dietary fat intake and exercise on inflammatory mediators of the immune system in sedentary men and women

OBJECTIVE

Dietary fat intake and exercise affect the immune system. This study determined the changes in inflammatory components of the immune system in response to maximal exercise with three levels of dietary fat intake: 19%, 30%, and 50% of total calories.

METHODS

Five men and six women were randomly assigned to consume diets with 19% and 50% calories from fat for three weeks each, with a one-week washout. The habitual and washout diets were 30% calories from fat. At the beginning and the end of each diet, body composition and maximal exercise tests were performed. Blood samples were collected before and after exercise to determine the immunological parameters.

RESULTS

The subject's energy intake was balanced to expenditure on the 30% and 50% diets, but was in negative balance on the 19% diet. Exercise led to significant increases in the concentrations of leukocytes, neutrophils, lymphocytes, monocytes, plasma tumour necrosis factor (TNF)-alpha, plasma interleukin (IL)-2, plasma soluble vascular cell adhesion molecule (sVCAM)-1, and the production of IL-1beta and IL-6 by peripheral blood mononuclear (PBMN) cells stimulated with lipopolysaccharide (LPS), irrespective of diets (p < 0.05). The 19% fat diet resulted in increased plasma soluble intercellular adhesion molecule (sICAM)-1 after exercise. Leukotriene (LT) B4 concentration released by neutrophils stimulated with LPS was higher in the 50% fat diet, compared to the lower fat diets, and the sICAM-1 production of neutrophils stimulated with LPS was significantly increased after exercise only with 30% fat diet.

CONCLUSION

While a short, intense bout of exercise increased pro-inflammatory mediators of the immune system, decreasing fat intake to 19% on a caloric deficient diet caused a greater increase in plasma TNF-alpha, sVCAM-1 and sICAM-1 concentration than the 30% and 50% fat diets in male and female subjects. Increasing fat calories to 50% with caloric balance did not exacerbate pro-inflammatory mediators compared to a 30% fat diet.

Effects of dietary fat on muscle substrates, metabolism, and performance in athletes

INTRODUCTION

The present investigation aimed at identifying differences in muscle structural composition, substrate selection, and performance capacity in highly trained endurance athletes as a consequence of consuming a high-fat or a low-fat diet.

METHODS

Eleven duathletes ingested high-fat (53% fat; HF) or high-carbohydrate diets (17% fat; LF) for 5 wk in a randomized crossover design.

RESULTS

In m. vastus lateralis, oxidative capacity estimated as volume of mitochondria per volume of muscle fiber (HF: 9.86 +/- 0.36 vs LF: 9.79 +/- 0.52%, mean +/- SE) was not different after the two diet periods. Intramyocellular lipid (IMCL) was significantly increased after HF compared with LF (1.54 +/- 0.27% vs 0.69 +/- 0.09%, P = 0.0076). Glycogen content was lower after HF than after LF, but this difference was not statistically significant (487.8 +/- 38.2 vs 534.4 +/- 32.6 mmol x kg-1 dry weight, P = 0.2454). Maximal power and [OV0312]O(2max) (63.6 +/- 0.9 vs 63.9 +/- 1.2 mL O(2) x min-1 x kg-1 on HF and LF) during an incremental exercise test to exhaustion were not different between the two diet periods. Total work output during a 20-min all-out time trial (298 +/- 6 vs 297 +/- 7 W) on a bicycle ergometer as well as half-marathon running time (80 min 12 s +/- 86 s vs 80 min 24 s +/- 82 s) were not different between HF and LF. Blood lactate concentrations and respiratory exchange ratios (RER) were significantly lower after HF than after LF at rest and during all submaximal exercise loads.

CONCLUSIONS

Muscle glycogen stores were maintained after a 5-wk high-fat diet period whereas IMCL content was more than doubled. Endurance performance capacity was maintained at moderate to high-exercise intensities with a significantly larger contribution of lipids to total energy turnover.

Influence of endurance running and recovery diet on intramyocellular lipid content in women: a 1H NMR study

Using a randomly assigned crossover design, we evaluated the change in intramyocellular lipid stores (IMCL) from baseline after a 2-h treadmill run [67% of maximal oxygen uptake (VO2 max)] and the recovery of IMCL in response to a postexercise very low-fat (10% of energy, LFAT) or moderate-fat (35% of energy, MFAT) recovery diet in seven female runners. IMCL was measured in soleus muscle by use of water-suppressed 1H-NMR spectroscopic imaging before (baseline), after, and approximately 22 h and 70 h after the run. IMCL fell by approximately 25% (P < 0.05) during the endurance run and was dependent on dietary fat content for postexercise recovery (P = 0.038, diet x time interaction). Consumption of the MFAT recovery diet allowed IMCL stores to return to baseline by 22 h and to overshoot (vs. baseline) by 70 h postexercise. In contrast, consumption of the LFAT recovery diet did not allow IMCL stores to return to baseline even by 70 h after the endurance run (P < 0.01 at 70 h). These results suggest that a certain quantity of dietary fat is required to replenish IMCL after endurance running.

Effects of dietary fat and endurance exercise on plasma cortisol, prostaglandin E2, interferon-gamma and lipid peroxides in runners

OBJECTIVE

Exercise and the neuroendocrine and oxidative stress it elicits on immune function is modulated by dietary fat intake. The effects of increasing dietary fat on endurance exercise-induced alterations 80% of VO2max for 2 hours) in the plasma levels of cortisol and prostaglandin E2 (PGE2), interferon-gamma (IFN-gamma) and lipid peroxides were investigated. As higher levels of cortisol, PGE2 and lipid peroxides could be immunosuppressive, the effects of different levels of dietary fat on these measures in runners were determined.

METHODS

Healthy trained runners (males and females) consumed serially 15% fat diet (of daily energy), 30% fat diet and 40% fat diets for four weeks each. In the last week of each diet period the subjects ran to exhaustion at 80% of their VO2max and blood was drawn pre- and post-run. Cortisol, IFN-gamma, PGE2 and lipid peroxides were determined using standard techniques.

RESULTS

Pre-exercise levels of plasma cortisol were elevated, IFN-gamma was unchanged and PGE2 and lipid peroxides decreased on the 40%F diet compared to 30%F and 15%F. Post-exercise levels of plasma cortisol (p < 0.004), PGE2 (p < 0.0057) and lipid peroxide levels increased (p < 0.0001) after endurance exercise on all diets. The rates of increase of plasma cortisol levels during exercise were similar on all three diets. Although absolute cortisol levels were higher in the high fat group, the rate of increase of plasma cortisol level during exercise was similar on each diet. The dietary fat levels did not affect IFN-gamma, however, PGE2 and lipid peroxides decreased with increasing fat at baseline at 40%F level (p < 0.01; 30%F vs. 40% F: p < 0.002; 15%F vs. 40%F: p < 0.007).

CONCLUSIONS

Data from the present study suggest that higher levels of fat in the diet, up to 40%, increase endurance running time without adverse effects on plasma cortisol, IFN-gamma, and lipid peroxide levels.

Dietary fats and immune status in athletes: clinical implications

Athletes are competitive, train at very high levels with inadequate rest, consume too few calories, avoid fats, and may be at increased risk of infections. The immune system is sensitive to both fat intake and intense exercise, suggesting that athletes may have suppressed immune function. It has been reported that many athletes consume about 25% fewer calories than the estimated expenditure, leading to low intakes of some essential micronutrients and fats. Acute exercise has been shown to increase inflammatory and decrease antiinflammatory immune factors and may increase oxidant stress. Chronic exercise appears to improve immune competence. Lipids are powerful mediators of the immune system, and they may modulate the immunosuppressive effects of strenuous exercise. Studies have shown that a low-fat high-carbohydrate diet (15% fat, 65% CHO, 20% protein of total calories), typically eaten by athletes, increases inflammatory and decreases antiinflammatory immune factors, depresses antioxidants, and negatively affects blood lipoprotein ratios. Increasing total caloric intake by 25% to match energy expenditure and the dietary fat intake to 32% in athletes appears to reverse the negative effects on immune function and lipoprotein levels reported on a low-fat diet. Increasing the dietary fat intake of athletes to 42%, while maintaining caloric intake equal to expenditure, does not negatively affect immune competency or blood lipoproteins, whereas it improves endurance exercise performance at 60-80% of VO2max in cyclists, soldiers, and runners. There is no evidence that higher fat intakes (up to 42% of total calories), in calorically balanced diets, increase the risk of cancer, but studies are needed to determine whether the beneficial effects of higher fat diets in athletes reduce their rate of infections.