The allure of rapid weight loss often leads individuals to explore very low-calorie diets (VLCDs), such as the 800-calorie diet. While this approach can yield quick results, it's crucial to understand the potential benefits, risks, and long-term implications before embarking on such a restrictive eating plan.
Understanding Very Low-Calorie Diets (VLCDs)
Very low-calorie diets (VLCDs) involve consuming significantly fewer calories than the average daily requirement. Typically, VLCDs restrict intake to 800 calories or less per day. This is in stark contrast to the recommended daily intake for women (1,600 to 2,400 calories) and men (2,000 to 3,000 calories).
These diets often utilize meal replacements like shakes, soups, or bars to ensure adequate nutrient intake while drastically reducing calories. VLCDs are different from over-the-counter meal replacements, which substitute one or two meals a day.
Potential Benefits of an 800 Calorie Diet
Rapid Weight Loss
The primary appeal of an 800-calorie diet is the potential for rapid weight loss. Individuals with a BMI over 30 may experience a loss of 3 to 5 pounds per week, resulting in an average total weight loss of 44 pounds over 12 weeks. This rapid weight loss can be particularly motivating for individuals seeking quick results.
Improvement in Medical Conditions
Even a modest weight loss of 5% of body weight can lead to improvements in various medical conditions, including:
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- Diabetes
- High blood pressure
- High cholesterol
The "Fast 800" diet, for example, is aimed at those wishing to lose weight, especially if they carry excess abdominal fat, as well as those with blood sugar issues, including pre-diabetes and type 2 diabetes. For those with type 2 diabetes, because stage one of the plan involves a very low-calorie diet, it may put your condition in to remission.
Use Before Weight-Loss Surgery
VLCDs are often used before weight-loss surgery for adults who have obesity and need to lose weight for health reasons.
Risks and Side Effects
While an 800-calorie diet can offer short-term benefits, it's essential to be aware of the potential risks and side effects.
Loss of Lean Body Mass
VLCDs can lead to a loss of lean body weight (LBW) and a decrease in resting metabolic rate (RMR). The addition of aerobic exercise does not prevent this. Loss of muscle mass can further slow down metabolism, making it harder to lose weight in the long run.
Nutrient Deficiencies
It's difficult to get good nutrition and feel satisfied on a very low-calorie diet. Improper nutrient intake may lead to nutrient deficiencies, impacting bodily functioning, energy levels, and cognitive abilities. Most people on very low calorie diets need vitamin and mineral supplements to ensure they are getting proper nutrition.
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Metabolic Slowdown
Consuming less than 1,000 calories daily can significantly impact metabolic rate. Scarcity of food intake prompts the body to lower the rate at which it burns calories to preserve energy, eventually making it harder to lose weight over time.
Bone Density Loss
Diet-induced weight loss can cause a temporary decrease in bone density. Although the effect can be reversed once the VLCD is stopped, long-term effects remain unclear.
Common Side Effects
People on a very low-calorie diet for 4 to 16 weeks report minor side effects such as:
- Fatigue
- Constipation
- Nausea
- Diarrhea
These conditions usually improve within a few weeks and rarely prevent people from completing the program.
Gallstones
Gallstones are the most common serious side effect of very low-calorie diets. Gallstones are more common during rapid weight loss. When the body experiences a calorie deficit, it starts to break down fat for energy. The liver then secretes more cholesterol and when combined with bile, can form gallstones.
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Who Should Avoid an 800 Calorie Diet?
Very low-calorie diets are not OK for everyone. Very low-calorie-diets are not recommended for:
- Pregnant or breastfeeding women
- Children or teens (except in specialized treatment programs)
- People over age 50 (depending on the potential need for medications for pre-existing conditions, as well as the possibility of side effects)
- People with diabetes who are insulin dependent
- Anyone with a history of an eating disorder
For people who are overweight but not obese (BMI of 27-30), very low-calorie diets should be reserved for those who have weight-related medical problems and are under medical supervision.
The Importance of Medical Supervision
A healthcare professional can assist in determining the appropriate weight loss plan based on an individual’s specific health background and goal weight. Medical supervision ensures optimal monitoring of nutrient deficiencies, side effects, and plan adjustments. If your BMI is greater than 30, then very low-calorie diets are generally safe when used under proper medical supervision.
Maintaining Weight Loss After an 800 Calorie Diet
Once you go off a diet, you need to change your lifestyle, committing to healthy eating and regular physical activity. People who lose weight very quickly are much more likely to regain the weight over time than people who lose weight slowly through less drastic diet changes and physical activity.
Transitioning to a Balanced Diet
After achieving the desired weight loss, transitioning to a balanced, nutrient-dense diet is crucial. This involves gradually increasing calorie intake while focusing on whole, unprocessed foods. The plan recognises that sustaining protein intake is important to maintain muscle mass and to support your metabolism and it encourages time-restricted eating to enhance the benefits of an overnight fast. A Mediterranean-style diet, with lean protein sources and vegetables, is often recommended.
Regular Physical Activity
Exercising regularly can encourage the burning of calories and preserve muscle mass. Additionally, it can boost your metabolism. Engage in cardio and strength training to promote weight loss and build muscle mass. In a study, the C+D group exercised 1 hour four times/week by walking, biking or stair climbing. The R+D group performed resistance training 3 days/week at 10 stations increasing from two sets of 8 to 15 repetitions to four sets of 8 to 15 repetitions by 12 weeks. Maximum oxygen consumption (Max VO2) increased significantly (p<0.05) but equally in both groups. Body weight decreased significantly more (p<0.01) in C+D than R+D. The C+D group lost a significant (p<0.05) amount of LBW (51 to 47 kg). No decrease in LBW was observed in R+D. In addition, R+D had an increase (p<0.05) in RMR O2 ml/kg/min (2.6 to 3.1).
Lifestyle Changes
Committing to long-term lifestyle changes is essential for maintaining weight loss. This includes:
- Adopting healthy eating habits
- Engaging in regular physical activity
- Managing stress
- Getting enough sleep
Alternatives to an 800 Calorie Diet
If the risks associated with an 800-calorie diet are a concern, several alternative approaches can promote sustainable weight loss.
Moderate Calorie Restriction
Diets that usually allow about 1,200 to 1,500 calories a day for women and 1,500 to 1,800 calories a day for men are recommended. You will not lose weight as fast with an LCD, but you can lose just as much weight with a VLCD.
Intermittent Fasting
Intermittent fasting does not require individuals to limit calorie intake unless they want to, making it a safe weight loss method. During eating windows, ranging in length, individuals can eat whatever foods they desire without counting calories.
Time-Restricted Eating
Time-restricted eating limits the number of hours per day that you can eat. A popular strategy is the 16:8. For this diet, you have to eat all of your meals during an 8 hour period, for example, 10 am to 6 pm. The rest of the time you cannot eat anything. There are some studies that this method can cause rapid weight loss, but there is little information so far about whether the weight loss is sustained.
Low-Carb or Keto Diet
Reducing carbohydrate intake while increasing fats and moderate protein consumption can help with weight loss. This is achieved by helping stabilize blood sugar and providing stable energy levels throughout the day resulting in less hunger during the day.
Plant-Based Diet
Eating plant-based foods such as vegetables, fruits, nuts, and whole grains encourages weight loss and lowers the risk of developing chronic diseases.