Have you ever heard weight loss advice that recommended eating smaller meals at more frequent intervals to help “speed up your metabolism”? Or come across the phrase “starvation mode,” referring to a fat storing effect that occurs when you don’t eat enough?
Advice like this often leads dieters to believe that leaving wide gaps of time between meals and eating too little might cause the metabolism to slow and eventually lead to weight gain. However, that’s not necessarily the case.
Simply put, if you repeatedly don’t eat enough calories to meet your body’s basic needs, you will lose both fat and muscle mass.
“You can never build mass when more is being burned than coming in,” says Sarah Waybright, a registered dietitian and the founder of WhyFoodWorks. “Chronically eating fewer calories than your body needs, especially ones that aren't nutrient dense won't lead to weight gain by itself.”
However, there are certain instances when under-eating or skipping meals may lead to weight gain. Waybright says that efforts to restrict calories by ignoring appetite can disrupt our hunger hormones and possibly lead to overeating later on.
“Studies show that people who are hungry tend to be more likely to reach for high-calorie junk foods instead of making healthy choices, so the initial effort to restrict can backfire,” says Waybright.
(She also pointed out that those who are chronically tired tend to show the same tendencies because sleep plays a large role in regulating hunger hormones, too.)
There’s a big difference between deliberately skipping meals and leaving more time between meals (or fasting intermittently) in order to support a healthy metabolism, though.
“The difference between the two is only in the intent, but that can make all the difference,” says Waybright. “Someone whose thought pattern is ‘I am fat, therefore I won't eat’ feels deprived and bad about themselves, while someone who thinks ‘I will mindfully fast so that I'm more in tune with my body's hunger cues’ is set up to use fasting as a tool to hone metabolism.”
According to Waybright, there’s a good deal of research that supports intermittent fasting as an effective strategy for weight and fat loss.
See also: What is the Intermittent Fasting Diet?
In fact, Waybright says that while there is such a thing as “starvation mode” (where your body might hold onto extra fat if it thinks food won’t be available soon), it won’t be activated by skipping one meal or leaving longer periods between meal times and that less frequent feedings won’t significantly slow your metabolism.
“Surging hunger hormones coupled with lowered blood sugar may cause people to reach for the wrong foods if they don't have a plan, but metabolism won't slow appreciably,” says Waybright.
However, she did go on to note that it’s important not to end a period of fasting with a mindset that says ‘I can eat whatever I want now.’
“A mindful fast is broken with a mindful meal that contains nutritious foods, ones that won't spike blood sugar and send you back to the kitchen hungry for more shortly thereafter,” says Waybright. “The key is to have a plan for what will be consumed at the end of a fast. ‘Skipping meals’ implies a lack of strategy.”
Waybright emphasized the fact that eating to prevent large spikes in insulin, which cause the body to store fat, is one of the most effective strategies for weight loss. This means avoiding refined carbohydrates like white flour and sugary drinks (including fruit juices, Waybright notes) and choosing nutrient rich foods that are high in protein and fiber.
“Keeping the body sensitive to insulin is also crucial,” says Waybright. “If cells are not responsive to it, the pancreas produces more and more to achieve an effect, which over time leads to diabetes and facilitates weight gain.”
Waybright says that regularly engaging in both cardiovascular and weight-bearing exercises is the best way to keep your cells insulin-sensitive. Plus, strength training workouts will increase your muscle mass and as a result, also increase your metabolism.
“Muscle mass raises metabolism,” says Waybright. “When people lose weight by cutting calories alone they almost always lose lean body mass along with fat. This is why it's crucial to do weight-bearing exercise to maintain muscle mass, and ideally eat to support that strenuous exercise.”