When you decide it's time to lose weight, you're motivated and ready to lose it fast. However, quick weight loss can be dangerous. Even if you know how many calories you should eat to lose 5 pounds per week, it's not a good idea unless you're under medical supervision.
The Basics of Weight Loss
While many factors, including hormones, healthy, age and genetics influence your ability to lose weight, the process of dropping pounds is usually boiled down to the equation of calories in versus calories out. Eat fewer calories than your body uses, and you should drop weight.
While this isn't a perfect equation, it's the one that makes you ask: "How many calories should I eat a day to lose 5 pounds a week?" Before that question is answered, however, realize that a safe and effective rate of weight loss recommended by experts, including those at the Centers for Disease Control and Prevention (CDC), is just 1 to 2 pounds per week.
People who lose weight at a slow, steady rate are more likely to keep off the pounds for the long-term and make the ongoing lifestyle changes that support good health forever. This may not bring you the short-term satisfaction of a quick reduction in pounds, but it will give major long-term benefits.
Calorie Needs for Weight Loss
If you're determined to use the calories-in/calories-out equation to lose weight, start by determining how many calories you need each and every day to simply maintain your current weight. While many complicated, involved equations are available, Harvard's Medical School recommends the simple act of multiplying your current weight by 15. For example, if you currently weigh 250 pounds, your calorie needs to stay at that weight are about 3,750 per day.
This provides a rough estimation of the number of calories you need to maintain your weight if you're moderately active (meaning you get at least 30 minutes, per day, of physical activity.) If you're not currently very active, build in an extra walk, take the stairs and do some chores to burn some calories.
When you want to lose weight, you need to reduce the number of calories you consume to a level below your maintenance threshold. One pound of fat, on your body, is equivalent to roughly 3,500 calories, so it's often recommended that you reduce your intake by 500 to 1,000 calories per day to safely lose the acceptable 1 to 2 pounds per week. In this example, that'd mean consuming 2,750 to 3,250 calories per day.
Losing 5 Pounds a Week
Now, losing 5 pounds a week requires a much larger calorie deficit. To lose 1 pound a week you need to reduce your intake by 3,500 calories over seven days, to lose 5 pounds you need to create a weekly deficit of 17,500 calories — or about 2,500 calories per day.
If you're that 250-pound person in the above example, you'll need to reduce your daily calorie intake to about 1,250 calories per day. This represents a serious reduction in the amount of food you eat. You're likely to feel extremely hungry, deprived and tempted to binge.
Harvard Medical School warns that dipping to this calorie level is putting you into potentially-risky territory, too. Dropping below 1,200 calories per day as a woman, or 1,500 calories as a man, can endanger your health, especially if you try to do so on your own.
Also, recognize that the 1,250-calorie-per-day recommendation is only if you're starting at 250 pounds. If you weigh less, you have different caloric needs, and need to take in even fewer calories to lose 5 pounds per week. You would most certainly fall below the minimum that you should aim to consume daily for good health. When it comes down to it, losing 5 pounds per week is just not a realistic goal. People who lose 5 pounds a week are usually those who have obesity that are on a medically-supervised weight-loss plan.
About Very Low-Calorie Diets
According to a study published by the National Clinical Guideline Centre in 2014, some people do attempt to pursue very low-calorie diets, or VLCDs, in an effort to lose a lot of weight quickly. These diets are defined as providing between 450 and 800 calories per day. They're often liquid-only or feature minimal solid food ,and must contain a full array of vitamins, minerals, electrolytes and fatty acids.
VLCDs should replace other food intake in a weight-loss program for a set period of time, and should only be followed under medical advisement and observation. UCLA Health notes that VCLDs are primarily for individuals with severe or life-threatening obesity who need to lose large amounts of weight in as safe a manner as possible to support their long-term health. The average weight loss on these VLCDs is 3 to 5 pounds per week.
When on a VCLD, you need careful monitoring by medical professionals. This is not something to try on your own, because this low a calorie intake is tantamount to starvation. Your weight, blood pressure, pulse rate and blood chemistry should be regularly measured while on a VCLD, to ensure that you're not experiencing extreme side effects due to the drastic caloric restriction.
It's even questionable whether VLCDs make a big difference in weight over the long run. The National Clinical Guideline Centre notes that after reviewing hundreds of studies on the topic, weight change was shown to change notably while people were on the diet plan. However, VLCDs didn't make much difference, compared to safer low-calorie plans, when it came to overall percentage of weight lost, ability to maintain the diet plan for the duration prescribed and long term weight maintenance.
Quick Weight-Loss Side Effects
The National Clinical Guideline Centre notes that VLCDs do have a very large potential to cause disordered eating, depression and postural hypotension, a form of low blood pressure.
The Academy of Nutrition and Dietetics confirms that extremely low-calorie plans and quick weight loss can have dire consequences. You may not get the nutrients you need, including vitamins, minerals and fiber, which could compromise your well-being and long-term health.
Consuming few calories for short-term weight loss can also interfere with the functioning of your metabolism. When you eat very little, your body senses that you're not taking in enough calories and consequently slows down all your bodily processes. You feel colder than usual, have less energy and may even experienced compromised digestion. Your mind also gets foggy; without optimal calories and fuel, it's just eking by.
The rapid weight loss you experience with very low calorie diets (and 5 pounds per week is considered very rapid) also increases your risk of developing gallstones. Gallstones cause severe abdominal pain and require surgery.
Healthy Weight Loss
Your desire to lose weight is commendable. Achieving a healthy weight greatly reduces your risk of chronic disease. Even losing 5 to 10 percent of your current weight, if you're overweight, can improve health markers such as blood pressure and cholesterol, explains the CDC. For a 250-pound person, that means losing 12.5 to 25 pounds.
Revisit your goals when it comes to weight loss and strive for a slower, steadier rate than 5 pounds per week. That doesn't mean you have to change your weight loss goal, just think again about how long it will take to reach it.
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It's even questionable if counting calories is really the way to go when you want to lose weight. Perspectives on Psychological Sciences published research in September 2017 questioning the calories-in/calories-out equation. The paper noted that reductions in your calorie intake are counteracted by your body's physical mechanisms.
When you greatly reduce calories, your metabolic rate slows down and your body increases its hunger signals — meaning that it's quite likely you regain any lost weight, if you even manage to stick to the diet at all. Reducing your calorie intake is likely to have only a limited, short-term influence in helping you manage your long-term weight.
Strategies for Weight Loss
Instead of simply tracking calories, look towards making smart dietary changes that support a healthy body and weight. For example, add more fresh fruits and vegetables. Eat whole grains in lieu of refined white bread and cereal. Choose broiled or baked chicken or fish over fried versions. Replace unhealthy saturated fat, such as butter and lard, with the health-supporting unsaturated fats of olive and avocado oils.
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Harvard Medical School also suggests creating an eating schedule, where you have meals and snacks planned for specific times during the day. Such consistency makes for successful weight-loss and weight maintenance.
Another important step in successful weight loss is getting off the couch and adding more physical activity. You don't have to commit to a marathon. Simply walk more often — maybe 10 minutes in the morning, in the afternoon and in the evening. Just get up from your seat more often, to fight the negative health effects of being sedentary.
The American Heart Association points out that any amount of movement is better than none. Short bouts add up over the course of a day. Ultimately, your goal is to achieve at least 150 minutes of moderate intensity activity, such as walking or gardening, per week. For weight loss and optimal health, getting closer to 300 minutes per week is even better. Work up to longer durations, and greater intensity levels, gradually.
- Harvard Health Publications: "Calorie Counting Made Easy"
- Academy of Nutrition and Dietetics: "4 Ways Low-Calorie Diets Can Sabotage Your Health"
- National Clinical Guideline Center: "Obesity: Identification, Assessment and Management of Overweight and Obesity in Children, Young People and Adults: Partial Update of CG43."
- UCLA Health: "Very Low Calorie Diet (VLCD)"
- Centers for Disease Control and Prevention: "Losing Weight"
- Perspectives on Psychological Science: "Reducing Calorie Intake May Not Help You Lose Body Weight"
- American Heart Association: "American Heart Association Recommendations for Physical Activity in Adults and Kids"