Can Eating Too Few Calories Lower Your Metabolism?
By Alina Petre
People trying to lose weight often restrict the number of calories they eat.
However, restricting calories too severely can lead to a variety of health problems, including reduced fertility and weaker bones.
This article describes five potentially harmful effects of calorie restriction and helps you determine the calorie deficit that's right for you.
Your Calorie Needs, Explained
A calorie is defined as the amount of heat energy needed to raise the temperature of one gram of water by 1 C (1.8 F).
However, you're more likely to think of calories as the unit of measurement for the amount of energy your body gets from the foods and beverages you consume.
Your body requires calories to function and uses them to sustain three main processes (1):
1. Basal metabolic rate (BMR): This refers to the number of calories needed to cover your basic functions, including the proper functioning of your brain, kidneys, heart, lungs and nervous system.
2. Digestion: Your body uses a certain number of calories to digest and metabolize the foods you eat. This is also known as the thermic effect of food (TEF).
3. Physical activity: This refers to the number of calories needed to fuel your everyday tasks and workouts.
Generally speaking, eating more calories than your body needs will cause you to gain weight, mostly in the form of body fat. Eating fewer calories than your body requires leads to weight loss (2, 3, 4).
However, restricting calories too much may harm your health in the following 5 ways.
1. It Can Lower Your Metabolism
Regularly eating fewer calories than your body needs can cause your metabolism to slow down.
What's more, this lower metabolism can persist long after the calorie-restricted diet is stopped (10).
In fact, researchers believe that this lower metabolism may partly explain why more than 80 percent of people regain weight once they go off their calorie-restricted diets (10).
To prevent your weight loss diet from affecting your metabolism, make sure that you never eat fewer calories than are required to sustain your BMR.
Summary: Severely restricting your calories can decrease your metabolism and cause you to lose muscle mass. This makes it more difficult to maintain your weight loss in the long term.
2. It Can Cause Fatigue and Nutrient Deficiencies
Regularly eating fewer calories than your body requires can cause fatigue and make it more challenging for you to meet your daily nutrient needs.
In addition, the number of carbs you eat may play a role in fatigue.
Calorie-restricted diets may limit other nutrients too, including:
- Protein: Not eating enough protein-rich foods like meat, fish, dairy, beans, peas, lentils, nuts and seeds may cause muscle loss, hair thinning and brittle nails (25).
- Calcium: Not eating enough calcium-rich foods like dairy, leafy greens, calcium-set tofu and fortified milks may reduce bone strength and increase the risk of fractures (26).
- Biotin and thiamine: A low intake of whole grains, legumes, eggs, dairy, nuts and seeds may limit your intake of these two B vitamins, potentially resulting in muscle weakness, hair loss and scaly skin (27, 28).
- Vitamin A: Not eating enough vitamin A-rich foods like organ meat, fish, dairy, leafy greens or orange-colored fruits and vegetables may weaken your immune system and lead to permanent eye damage (29).
- Magnesium: An insufficient intake of magnesium-rich whole grains, nuts and leafy greens may cause fatigue, migraines, muscle cramps and abnormal heart rhythms (30).
To prevent fatigue and nutrient deficiencies, avoid overly restricting your calories and ensure you eat a variety of whole, minimally processed foods.
Summary: Restricting calories too severely can lead to fatigue. Maintaining this calorie restriction for too long can also lead to nutrient deficiencies.
3. It May Reduce Fertility
Restricting calories too dramatically can negatively affect fertility. This is especially true for women, as the ability to ovulate depends on hormone levels.
Accordingly, studies show that reproductive function is suppressed in women who eat 22–42 percent fewer calories than are needed to maintain their weight (33).
Signs of reduced fertility may include irregular menstrual cycles or a lack of them. However, subtle menstrual disturbances may not have any symptoms, so they may require a more thorough medical examination to be diagnosed (37, 38).
Researchers believe that severe calorie restriction may also affect men's reproductive function, but few studies exist on the topic (39).
Summary: Overly restricting calories may potentially reduce fertility, especially in women. More studies are needed to determine the effects of calorie restriction in men.
4. It Can Weaken Your Bones
Consuming too few calories can weaken your bones.
That's because calorie restriction can reduce estrogen and testosterone levels. Low levels of these two reproductive hormones are thought to reduce bone formation and increase bone breakdown, resulting in weaker bones (40, 41, 42, 43).
In addition, calorie restriction — especially when combined with physical exercise — can increase stress hormone levels. This may also lead to bone loss (44).
Summary: Restricting calories may disturb hormone levels, which may result in weaker bones and an increased risk of fractures.
5. It May Lower Your Immunity
Restricting calories may increase your risk of infections and illness.
For instance, one study compared athletes in disciplines that put a strong emphasis on body leanness, such as boxing, gymnastics or diving, to those in disciplines less focused on body weight.
The researchers reported that athletes in disciplines that required leanness made more frequent attempts to lose weight and were almost twice as likely to have been sick in the previous three months (47).
In another study, taekwondo athletes who were dieting to reduce their body weight in the week before a competition experienced reduced immunity and an increased risk of infection (48).
The effects of calorie restriction in non-exercising individuals are less clear and more research is needed before strong conclusions can be made (49).
Summary: Calorie restriction, especially when combined with strenuous physical activity, may lower your immune defenses.
How to Eat the Right Number of Calories
Calorie needs vary from person to person because they depend on factors such as age, sex, height, current weight and physical activity level.
Determining the number of calories that's right for you will reduce your likelihood of developing the negative health consequences outlined above.
There are various ways to estimate your own calorie needs. The easiest method consists of three simple steps:
1. Determine your BMR: Use this online calculator to estimate the minimum number of calories your body requires per day. Aim to never consume fewer calories than this.
2. Estimate your daily requirement: Use this online calculator to estimate the number of calories you need to maintain your current body weight.
3. Determine your calorie needs for weight loss: If weight loss is your goal, aim for a daily calorie intake falling between the amount required to sustain your BMR and the amount needed to maintain your current body weight.
In addition, make sure you record what you eat in an online food journal like Cronometer, at least in the beginning of your weight loss process.
Tracking your diet will help you ensure that you continue to reach your daily recommended nutrient intakes.
Summary: Use the method above to estimate the daily calorie intake that's right for you, in addition to an online diet journal to ensure your diet covers your nutrient needs.
The Bottom Line
When it comes to long-term weight loss, patience is key. It's best to steer clear of diets that require you to severely restrict your calories.
Instead, opt for diets that are focused on diet quality and encourage you to make sustainable lifestyle changes.
Reposted with permission from our media associate Authority Nutrition.
Material Revolutions: Shirts Made from Shellfish, Biodegradable Rum Bottles and Reusable Fast Food Containers
In the age of consumption, sustainability innovations can help shift cultural habits and protect dwindling natural resources. Improvements in source materials, product durability and end-of-life disposal procedures can create consumer products that are better for the Earth throughout their lifecycles. Three recent advancements hope to make a difference.
1. Allbirds Shirts Made From Shellfish<p>Sustainable sneaker start-up <a href="https://www.allbirds.com/pages/apparel" target="_blank">Allbirds</a> is known for its thoughtfulness for consumers and the environment. The four-year-old shoe company has become hugely popular by creating comfortable shoes made from responsibly sourced materials like tencel and wool, reported <a href="https://www.fastcompany.com/90565358/allbirds-new-clothing-line-includes-t-shirts-made-from-discarded-crab-shells" target="_blank">Fast Company</a>.</p><p>Recently, Allbirds launched its debut apparel line with garments for men and women made with eco-friendly materials that have a low carbon footprint, the report said.</p><p>Introduced along with the line is a new t-shirt material called "TrinoXO," which is made from wool and discarded snow crab shells from Canada's seafood industry, reported <a href="https://www.cnbc.com/2020/10/20/sustainable-sneaker-start-up-allbirds-is-selling-sweaters-t-shirts.html" target="_blank">CNBC</a> and <a href="https://www.cnn.com/2020/10/20/business/allbirds-sustainable-apparel/index.html" rel="noopener noreferrer" target="_blank">CNN</a>. The shells are the "number two discarded resource on earth," Allbirds claims, reported <a href="https://www.menshealth.com/style/a34427585/allbirds-apparel-clothing-line-review/" rel="noopener noreferrer" target="_blank">Men's Health</a>.</p><p>"Discarded material is the holy grail when it comes to sustainable fibers," Jad Finck, Allbirds head of innovation and sustainability, told Fast Company. "It's far better for the environment than getting raw materials from scratch."</p><p>The shells have antimicrobial properties that keep clothes fresh even after hours of wear, without the need to add "extractive" materials like zinc or silver, Men's Health reported. This allows for longer periods of wear between washes, reducing clothes' environmental footprint.</p><p>"We knew we wanted to be a real brand, and had this vision that we'd be an innovation company first, and a product company second," co-founder Joey Zwillinger told <a href="https://www.vogue.com/article/allbirds-launches-clothing" rel="noopener noreferrer" target="_blank">Vogue</a>. "And our products would solve problems for people in a natural way, and show the world that you don't have to compromise on the planet for amazing products."</p>
2. Bacardi Biodegradable Rum Bottles<p>By 2023, <a href="https://www.bacardi.com/us/en/" target="_blank">Bacardi</a> rum will be sold in 100% biodegradable bottles, <a href="https://www.businesswire.com/news/home/20201021005281/en/Bacardi-First-in-Fight-Against-Plastic-Pollution-With-100-Biodegradable-Spirits-Bottle" target="_blank">Business Wire</a> reported.</p><p>The alcohol giant is collaborating with Danimer Scientific, a leading developer of biodegradable products, to create the new bottles using the natural oils of plant seeds such as palm, canola and soy, the report said.</p><p>According to <a href="https://sports.yahoo.com/bacardi-to-make-100-biodegradable-spirits-bottle-124436841.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_sig=AQAAAE1Wl8ONNdph3ID8reylzGM8dbX575Mk96Jw6z3kHZaGjKCz_UgQgxH0Q1n3RNCzhOMBEZ7fAIf8iiOXLRtY9VVHNZsmb-w1VOJnGlzIbuwhmoBo_KOV4dba8FoWrkgmmwwCyQZnRoTL0Uda6HQ4pE5ewGWh2pwQzjS3gKAe1ynm" target="_blank">Yahoo Finance UK</a>, the new bottle will biodegrade in a wide range of environments, including compost, soil, freshwater and seawater. After 18 months, the bottle will disappear completely without leaving microplastics.</p><p>"Nodax PHA is one of the most promising eco-friendly materials in the world today because it delivers the biodegradability that consumers demand without losing the quality feel they receive from traditional plastic," said Danimer Scientific chief marketing & sustainability officer Scott Tuten, reported <a href="https://www.thrillist.com/news/nation/bacardi-biodegradable-spirits-bottle-plastic-free-packaging" target="_blank" rel="noopener noreferrer">Thrillist</a>. "The material provides the best of both worlds, and we look forward to working with Bacardí and incorporating PHA into their iconic packaging."</p><p>Bacardi is also creating a sustainably sourced paper bottle, Yahoo reported.</p><p>The manufacturing of both new bottle types will save energy over petroleum-based plastic ones. Bacardi plans to share the technology with competitors to help in the global fight against <a href="https://www.ecowatch.com/tag/plastic-pollution" target="_self">plastic pollution</a>, and aims to be 100% plastic-free by 2030, reported Thrillist.</p>
3. Burger King Reusable Fast Food Containers<p>Fast food giant <a href="https://www.bk.com/" target="_blank">Burger King</a> plans to launch reusable Whopper boxes and soda cups by next year. Partnering with TerraCycle's zero-waste packaging division Loop, Burger King will nudge customers to return the specialized packaging for hygienic washing and reuse, similar to how milk bottles used to be returned, reported <a href="https://www.marketwatch.com/story/can-burger-kings-reusable-packaging-change-fast-food-forever-11603392581" target="_blank">MarketWatch</a>.</p><p>"During COVID, we have seen the environmental impact of <a href="https://www.ecowatch.com/air-pollution-food-delivery-plastic-waste-2648454324.html" target="_self">increased takeaway ordering</a>, which makes this initiative by Burger King all the more important," said Tom Szaky, TerraCycle and Loop CEO, according to MarketWatch.</p><p>Customers who don't feel comfortable can opt-out of the service, <a href="https://www.abc10.com/article/entertainment/television/programs/the-buzz-burger-king-to-test-reusable-packaging-in-2021/77-f01f1b70-05b7-436d-9971-a7dd6081249b" target="_blank">ABC News</a> reported. Those who are willing to try will be charged a small deposit upon purchase, and when the packaging is returned, they will receive a refund, reported <a href="https://www.cnn.com/2020/10/22/business/burger-king-reusable-packaging-sustainability/index.html" rel="noopener noreferrer" target="_blank">CNN</a>.</p><p>Burger King and TerraCycle are aiming for a container that can be used at least 100 times, reported <a href="https://www.fastcompany.com/90566995/burger-kings-new-whopper-packaging-isnt-greasy-cardboard-its-reusable" rel="noopener noreferrer" target="_blank">Fast Company</a>.</p><p>"The benefit is, you're able to serve your guests without having to create that single-use item in the first place," Matt Banton, global head of innovation and sustainability at Burger King, told <a href="https://www.fastcompany.com/90566995/burger-kings-new-whopper-packaging-isnt-greasy-cardboard-its-reusable" rel="noopener noreferrer" target="_blank">Fast Company</a>. "This product is durable enough to go through the system multiple times, so it's ultimately reducing our environmental impact, and minimizing the amount of single-use packaging that we have to produce as well."</p><p>Burger King has also committed to sourcing 100% of its customer packaging from renewable, recycled or certified outlets, and recycling all customer packaging at its restaurants in the United States and Canada by 2025, reported CNN.</p>
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The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.
"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."
The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.
They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.
They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.
But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.
"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.
What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.
It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.
To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.
First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.
Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.
University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.
"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."
Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.
"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.
There are many different CBD oil brands in today's market. But, figuring out which brand is the best and which brand has the strongest oil might feel challenging and confusing. Our simple guide to the strongest CBD oils will point you in the right direction.
In 'Road Map for a More Sustainable Future,' NY Regulator Tells Banks to Consider Climate Risks in Planning
By Brett Wilkins
Regulators in New York state announced Thursday that banks and other financial services companies are expected to plan and prepare for risks posed by the climate crisis.
A NASA spacecraft has successfully collected a sample from the Bennu asteroid more than 200 million miles away from Earth. The samples were safely stored and will be preserved for scientists to study after the spacecraft drops them over the Utah desert in 2023, according to the Associated Press (AP).