Most of today’s common major diseases are metabolic in nature, meaning they have to do with how the body processes energy. Diabetes and heart disease top the list of metabolic diseases. In a new study published in Nutrition & Metabolism, researchers from Boston College have proposed that cancer is also fundamentally a metabolic disease. They argue that “essentially all hallmarks of cancer… can be linked to impaired mitochondrial function and energy metabolism.”

If this new hypothesis gains general acceptance, it could lead to major changes in how cancer is prevented and managed. Specifically, they suggest the cancer can be “starved”. They write, “Two major conclusions emerge from the hypothesis; first that many cancers can regress if energy intake is restricted and, second, that many cancers can be prevented if energy intake is restricted. Consequently, energy restricted diets combined with drugs targeting glucose and glutamine can provide a rational strategy for the longer-term management and prevention of most cancers.

Numerous studies have shown that creatine supplementation enhances the strength and muscle mass gains that result from strength training. However, most of these studies have involved young men. Researchers from the University of Oklahoma recently sought to determine whether middle-aged and older men engaged in strength training also benefit from creatine supplementation. Forty-two men between the ages of 48 and 72 years completed 14 weeks of resistance training while receiving either placebo, creatine, creatine and protein, or protein daily. The members of all four groups experienced similar gains in strength and muscle mass during the intervention. The authors of the study, which was published in the Journal of Nutrition, Health and Aging, thus concluded that creatine and protein supplementation conferred no addition benefits on middle-aged and older men engaging in strength training.

Doctors typically advice patients with high blood pressure to adopt the DASH diet, a low-fat-, low-sodium diet endorsed by the American Heart Association. Research has shown that it works, but exercise has also been shown to reduce hypertension. So how do diet and exercise together compare to the DASH diet alone? Researchers from Duke University Medical center recently studied this question. One hundred-forty four overweight patients with high blood pressure were separated into three groups. One group was given a set of standard dietary guidelines for control of hypertension. A second group was instructed to follow a strict DASH diet. And the third group was instructed to follow the DASH diet and exercise regularly. On average, standard dietary controls lowered blood pressure by 3.4 mm Hg. The DASH diet lowered blood pressure by 11.2 mm Hg. And the DASH diet plus exercise lowered blood pressure by 16.1 mm Hg. So there’s your answer. The study was published in the Archives of Internal Medicine.

Glycerol is a natural compound that is similar in chemical structure to alcohol. It is present in the body in stored fat and in fluids and can also be purchased as a supplement to promote water retention. One effect of ingesting glycerol is an increase in blood plasma volume, which is potentially beneficial to athletes because it could slow the dehydration process during exercise. The journal Sports Medicine has published a new review on the use of glycerol for pre-exercise “hyperhydration” by researchers at the University of Queensland, Australia. In analyzing the results of numerous previous studies they conclude that glycerol is effective in hyperhydrating athletes before exercise, delaying dehydration during exercise, and improving thermoregulation during exercise and endurance performance. As for the proper protocol for glycerol use in pre-exercise fluid loading, the authors of this review report that “endurance athletes intending to hyperhydrate with glycerol should ingest glycerol 1.2 g/kg BW in 26 mL/kg BW of fluid over a period of 60 minutes, 30 minutes prior to exercise.”

Exercise scientists use the body’s testosterone-cortisol ratio (T:C) as one marker of overreaching and overtraining. Testosterone is an “anabolic” hormone, and testosterone levels tend to be higher when the body is being built up. Cortisol is a “catabolic” hormone, and cortisol levels tend to be higher when the body is being broken down. Thus, a low T:C ratio is associated with classic symptoms of overtraining, including performance decline. Carbohydrate intake influences the T:C ratio in athletes, mostly indirectly, by providing fuel for training and recovery. When carbohydrate intake is inadequate for any given training load, the T:C ratio is likely to decrease.

This was shown in a new study by researchers at the University of North Carolina. Twenty male subjects were subjected to three consecutive days of unaccustomedly challenging endurance exercise. Twelve of the 20 were placed on a 60 percent carbohydrate diet during this crash training camp, while the other eight were placed on a 30 percent carbohydrate diet. The authors of the study, which was published in the European Journal of Applied Physiology, found that the T:C ratio did not change over the three days of heavy training in the high-carbohydrate group but declined significantly in the low-carbohydrate group.

This is evidence that, to a point, the more carbohydrate you consume, the more training your body can handle.

Everyone knows that successful runners are always light and lean, but a new study by researchers at the University of Zaragosa, Spain, suggests that body fat percentage is as important to running performance as any physiological factor. The Spanish scientists used skinfold measurements to estimate body fat percentage in 12 elite male and 12 elite female Ethiopian distance runners and compared these estimates to their race performances. They found an 80 percent correlation between skinfold measurements and race times in the men and a 78 percent correspondence in the women. All of these runners were very lean, but the leanest among them were the fastest. Body fat estimates were comparable to other physiological measurements such as forced expiratory volume in predicting performance. The study was published in the Journal of Sports Medicine and Physical Fitness.

This may be my favorite new study of the last several months. Italian researchers have proven that if you eat when you’re hungry, and only when you are hungry, you will lose weight if you are overweight and sustain your weight if you are not overweight. It sounds absurdly simple, and on one level it is, but it is a simple idea that has been obscured by certain complexities.

The core concept is that eating behaviors are regulated by both physiological sensations linked to specific underlying physiological events such as declining blood glucose levels and by conditioning, such as the conventions of eating breakfast, lunch and dinner at certain times of day. “Initial hunger” is a term that refers to the purely physiological triggers of eating. The authors of this new study hypothesized that initial hunger is the body’s true guide to how much food it needs. They further proposed that overweight individuals who were trained to recognize and respond to initial hunger–eating only when they were truly hungry instead of always at planned meal times, when food happened to be available, etc–would lose weight.

And guess what? In five months, the subjects trained to eat only when hungry for this study lost more than 10 pounds, on average–far more than members of a control group who were encourage to lose weight by means of general eating restraint (which is known to be ineffective because it is unsustainable). The study was published in Nutrition & Metabolism.

The European Journal of Applied Physiology has published a new study on the effects of caffeine on supramaximal cycling performance. Researchers from Australia’s Griffith University recruited highly trained cyclists to complete indoor rides to exhaustion at 120 percent VO2max. They performed the test on two occasions, once after taking caffeine and once after taking placebo. Time to exhaustion was significantly greater following caffeine ingestion.

The researchers took several measurements to determine the cause of the performance increase with caffeine. No significant physiological differences were found except that circulating levels of potassium ions (K+) were lower during the warm-up in the caffeine trial. Since the accumulation of potassium ions outside muscle cells contributes to fatigue at very high exercise intensities, the apparent lowering of K+ levels after caffeine ingestion may have increased the amount of time it took for K+ accumulation to reach critical levels during the performance trial.

Recently we told you about a new study showing that dehydration ruins weightlifting performance. Now along comes a study from Charles Sturt University in Australia showing that dehydration has little effect on repeated sprint performance in the heat. The subjects were nine male rugby players, who were required to perform two 50-minute workouts consisting of 15m sprints followed by hard running, jogging and walk to fill the balance of one minute. During one of the workouts the subjects were allowed to drink fluid to minimize dehydration. During the other workout they went thirsty.

The authors of the study, which was published in the Journal of Sports Science, reported that there were no differences in sprints times or distances covered in the two sessions, although the subjects slowed slightly more toward the end of the dehydrated workout then they did in the hydrated workout. There were also no differences in heart rate, core temperature, nude mass, capillary blood haematocrit, pH, lactate concentration, perceptual ratings of perceived exertion, or thermal stress. The only difference between the two session was that the subjects were thirstier after the one in which they did not drink!

HMB—known to scientists as beta-hydroxy beta-methylbutyrate—is a metabolite of the essential amino acid leucine. HMB became popular as a muscle and strength building supplement in the 1990s due to speculation that it might limit muscle protein degradation following resistance exercise and enhance positive nitrogen balance. The effects of HMB on muscle and strength gains resulting from resistance training have since been investigated in numerous studies. Some have shown that it is effective, while others have shown that it is not. The majority of studies showing benefits have been poorly designed. A majority of the well-designed studies have shown no benefit. Also, most studies showing beneficial effects of HMB supplementation have involved beginning weightlifters, while most studies involving trained weightlifters have shown no benefit.

More recent studies have looked beyond muscle strength and growth toward other possible benefits of HMB supplementation, but they have also come up empty. The most recent study was performed by researchers at England’s Kingston University and published in the Journal of Strength and Conditioning Research. This study looked at the effect of supplementation with HMB and alpha-ketoisocaproic acid on muscle damaged induced by downhill running. These supplements were found to have no effect on muscle damage biomarkers or muscle soreness in the 72 hours after a 40-minute downhill run.