Intermittent Fasting is a popular weight loss method that focuses on ‘when’ you eat. This can include meal skipping, eating only within a window of time during the day, eating every other day, or alternating a set number of fasting days with eating days. Evidence shows when we restrict meals, there’s less likelihood of a rise in insulin and other hormones contributing to weight gain.
Hundreds of studies done on animals (rats) show Intermittent Fasting benefits. Human clinical trials are fewer and short-term but also find several benefits in lowering the risk of obesity, diabetes, cardiovascular disease, cancers and neurological disorders.
One benefit is the potential for improved insulin response: insulin levels decrease without constant food intake, allowing fat cells to release their stored sugar to be used as energy. So, we can lose weight if we lower our insulin levels. However, Intermittent Fasting can’t take sole claim for this process.
Two recent studies were completed in 2022, including a long-term one that lasted a year. Both confirmed many past researched benefits. However, the results across the board, including insulin response, were no more impressive than following a calorie-restricted diet. Therefore, it’s suspected the benefits of Intermittent Fasting are likely due to calorie restriction.
Can Intermittent Fasting lengthen lifespan? Animal studies show mixed results and human studies on Intermittent Fasting were too short for evidence of long-term effects. The jury is still out on calorie restriction for longevity.
An internet surf finds plenty of encouraging reports on Intermittent Fasting, but it’s wise to verify a report’s credibility. Notice how current the information is, that the studies cited also include relevant contradictory studies, and be careful if the source is also selling products. Most important: a credible, unbiased source will mention the possible side effects or cautions.
Fasting can be potentially harmful. It’s not recommended for pregnant and breastfeeding women, young children, people taking medications, and those with hormonal imbalances or immune deficiencies, particularly after organ transplants.
People with eating disorders or dementia have other challenges that can be exacerbated by fasting. And while people at risk for diabetes may benefit from the improved insulin response of a lower-calorie diet, those with advanced diabetes or taking medications for it should be medically supervised – or avoid fasting.
Athletes or anyone doing high-intensity activities should also be careful when fasting. Perhaps limit your more intense training sessions to your non-fasting days. You need the fuel!
Adults of advanced age should also exercise caution with Intermittent Fasting. There isn’t enough evidence of the risk for older adults, as the trials involved young or middle-aged adults. If you have only marginal weight loss needs, losing more weight can negatively affect bones, the immune system, and energy levels. While these risks apply to everyone, they are amplified in older individuals. In addition, older adults who must take medications with food could find it challenging when fasting. And those taking heart or blood pressure medications may risk dangerous imbalances in potassium and sodium.
If any of these cautions apply to you, but you still want to try Intermittent Fasting, talk with your doctor. If it’s determined you can follow the diet, your doctor and/or a Registered Dietitian can design a plan and monitor your progress.
Use common sense with Intermittent Fasting: avoid overeating yet get enough calories (don’t skip meals) on non-fasting days – especially if you exercise intensely! And focus on those nutrient-rich whole or ‘unchanged’ food sources rather than the nutrient-poor, ultra-processed foods.
No single eating plan or ‘diet’ is best for everyone because we are all different with unique needs. For relatively ‘healthy’ people, however, Intermittent Fasting can be a safe option for weight loss. A diet will only work if you can stick to it. So perhaps Intermittent Fasting is the diet plan that will work for you.
Eve Lees has been active in the health & fitness industry since 1979. Currently, she is a Freelance Health Writer for several publication and speaks to business and private groups on various health topics.