Fasted Workout Update
Even though there is some evidence of advantages to fasted workouts, there is also evidence that suggests fueling with carbohydrates and protein before exercise can improve performance, minimize muscle damage, and prevent depletion of glycogen.
Fasted Workout Update
Schoenfeld BJ, Aragon AA, Wilborn CD, Krieger JW, Sonmez GT. Body composition changes associated with fasted versus non-fasted aerobic exercise. J Int Soc Sports Nutr. 2014;11(1):54. doi:10.1186/s12970-014-0054-7
One review found that, in several studies, fasted exercise led to higher metabolic performance after the workout was complete. However, the same review noted that for prolonged aerobic activity, eating before the workout enhanced performance (1).
This research illustrates that while fasted cardio may burn more calories than nonfasted cardio during the session itself, the difference it makes to total daily calorie expenditure in a span of 24 hours is trivial.
Morning workouts are awesome: Aside from the convenience of getting it done and being on with your day, first-thing-in-the-a.m. sessions have been shown to boost energy all day long. But one of the much-debated and heated arguments in the fitness and nutrition world revolves around whether or not you should eat before those early sessions. So, we spoke to the experts, combed through the latest research, and compiled the pros and cons of fasted workouts.
There are a few different ways to take advantage of intermittent fasting, which I learned about from Martin over at LeanGains, a resource specifically built around fasted strength training:
NF Journey will guide you through a workout routine that can be done anywhere, all while creating your very own superhero! No guesswork needed, just follow the progression plan laid out in the app and grow strong!
A fasted state occurs when you have not eaten for 10-12 hours prior to exercise. This allows for glycogen stores to be fully depleted and means that the body has stopped breaking down food. In theory, this would facilitate increased fat burning by lowering insulin levels and depleting glycogen stores enough that body fat would be broken down and burned as free fatty acids for fuel.
A beta-analysis from 2017 looking at five studies on fasted versus fed exercise concluded that working out fasted does not result in greater weight loss or changes in lean muscle mass or fat mass. Although fasted workouts do increase fat burning, it does not translate to decreased body fat levels like changes in long-term caloric balance does.
In addition to not seeing significant effects on fat loss from fasted training, the tactic could result in poor performance and longer recovery times. There is an increase in protein breakdown that occurs as the body attempts to find fuel before it seeks fat as a fuel source.
However, we do see that there are a few scenarios in which fasted training can be beneficial. For those individuals who are training for ultra-endurance events and will have limited access to fuel during the event, this type of training can prepare them for prolonged exercise on minimal fuel. Additionally, performing low-intensity exercise, such as walking, in a fasted state may be better as eating beforehand can blunt the fat burning effects that occur as a result.
Several studies also show a link between fasted cardio and improved endurance. The mechanism through which this occurs is an increase in VO2 max, which is the maximum amount of oxygen used during exercise. Fasted cardio has been shown to increase your ability to take in and deliver oxygen to your muscles, allowing you to train harder, especially during high intensity training sessions.
The Feature Paper can be either an original research article, a substantial novel research study that often involvesseveral techniques or approaches, or a comprehensive review paper with concise and precise updates on the latestprogress in the field that systematically reviews the most exciting advances in scientific literature. This type ofpaper provides an outlook on future directions of research or possible applications.
Abstract:It remains unclear whether training in fasted compared to fed states leads to greater weight loss and whether this practice results in beneficial or detrimental changes in body composition. We conducted a systematic review to examine the effect of overnight-fasted versus fed exercise on weight loss and body composition. Seven electronic databases were searched using terms related to fasting and exercise. Inclusion criteria were: randomised and non-randomised comparative studies; published in English; included healthy adults; compared exercise following an overnight fast to exercise in a fed state; used a standardized pre-exercise meal for the fed condition; and measured body mass and/or body composition. A total of five studies were included involving 96 participants. Intra-group analysis for the effect of fasted and fed aerobic exercise revealed trivial to small effect sizes on body mass. The inter-group effect for the interventions on body mass was trivial. Intra-group effects were small for % body fat and trivial for lean mass in females, with trivial effects also found for the inter-groups analyses. Whilst this is the first systematic review and meta-analysis to investigate this topic, caution is warranted when interpreting the findings due to the limited number of studies and hence insufficient data. Keywords: weight loss; obesity; caloric restriction; exercise training
The results of this study in the Journal of Clinical Endocrinology and Metabolism further confirms the benefits on fasting cardio before breakfast for maximum fat loss! When you eat a meal or carbohydrate before a workout, you increase levels of insulin, which enhances fat storage and inhibition of fat mobilization, oxidation and fat burning. You do not want to release insulin before cardio if you want to burn more fat. By fasting on an empty stomach before cardio, your body can shift fuels from burning glucose to burning fat. The research shows that fasted cardio before breakfast will not result in loss of muscle tissue to a greater extent than cardio in the fed state.
A June 1, 2018, study published in the International Journal of Exercise Science reported that 10-hour fasting before a resistance training workout enhanced fat oxidation and fat burning. There are only a few studies that looked at the long-term effects of fasted cardio on body composition. The British Journal of Nutrition compared a morning run and eating an early breakfast or while in a fasted state. Not having breakfast resulted in 20% more fat being burned!
The scientific research has shown that fasted cardio could be an exciting and promising method for weight loss, fat loss, weight control and metabolic health. The research shows that for someone with stubborn body fat, as well as someone who is lean, and wants to get ripped, then fasted cardio before breakfast can enhance more abdominal fat and intramuscular fat burning!
It has been hypothesized that performing aerobic exercise after an overnight fast accelerates the loss of body fat. The purpose of this study was to investigate changes in fat mass and fat-free mass following four weeks of volume-equated fasted versus fed aerobic exercise in young women adhering to a hypocaloric diet. Twenty healthy young female volunteers were randomly assigned to 1 of 2 experimental groups: a fasted training (FASTED) group that performed exercise after an overnight fast (n = 10) or a post-prandial training (FED) group that consumed a meal prior to exercise (n = 10). Training consisted of 1 hour of steady-state aerobic exercise performed 3 days per week. Subjects were provided with customized dietary plans designed to induce a caloric deficit. Nutritional counseling was provided throughout the study period to help ensure dietary adherence and self-reported food intake was monitored on a regular basis. A meal replacement shake was provided either immediately prior to exercise for the FED group or immediately following exercise for the FASTED group, with this nutritional provision carried out under the supervision of a research assistant. Both groups showed a significant loss of weight (P = 0.0005) and fat mass (P = 0.02) from baseline, but no significant between-group differences were noted in any outcome measure. These findings indicate that body composition changes associated with aerobic exercise in conjunction with a hypocaloric diet are similar regardless whether or not an individual is fasted prior to training.
The provision of nutrients prior to aerobic exercise has been shown to have a profound impact on the physiological response to the training bout ,. Accordingly, a number of strategies have been devised to take advantage of this phenomenon. One such strategy involves training after an overnight fast to accelerate the loss of body fat . In theory, low glycogen and insulin levels cause the body to shift energy utilization away from carbohydrates, thereby allowing greater mobilization of stored fat for fuel. Findings from several acute studies appear to support this contention, with exercise in the fed state resulting in a reduced entry of long-chain fatty acids in the mitochondria and a corresponding decrease in fat oxidation -. These results in the fed state have been attributed to an insulin-mediated attenuation of adipose tissue lipolysis, an increased glycolytic flux, and/or a decreased expression of genes involved in fatty acid transport and oxidation -. There also is evidence that consistent exercise while fasted results in chronic molecular adaptations favorable to fat oxidation. For example, 6 weeks of fasted aerobic training increased the content of intramuscular fatty acid binding protein and uncoupling-protein-3 content to a greater extent than training post-prandially . In addition, regimented fasted training has been shown to promote superior improvements in whole-body glucose tolerance and insulin sensitivity as well as upregulating various lipolytic enzymes compared to exercising while fed ,.