How Long Does It Take To Lose Weight?

We live in a ‘have it now’ culture and many people view weight loss in a similar fashion; the desire for quick results can be strong.

However, rapid crash dieting is rarely the best approach to sustainably lose weight. In truth, the amount of time it takes to lose weight can vary from person to person depending on factors including the goal, the starting weight, and the degree of energy restriction.

Guidance from the U.S. Centers for Disease Control and Prevention (CDC) recommends aiming for gradual, steady weight loss at around 1–2 lb (0.5–1 kg) per week. While this may sound small at first glance, it is equivalent to losing 4–8 lbs over four weeks, 12–24 lbs over 12 weeks, and approximately 26–52 lbs in six months, all of which represent substantial weight loss.

In this article, we examine the facts, scientific studies, and nuances behind the question of how long it takes to lose weight. We also provide some evidence-based insights into the factors that can influence the rate of weight loss.

The Progressive Results of Steady Weight Loss

When you talk to someone who wants to lose weight, you’ll often hear them state a relatively high weight loss target that they want to reach for an upcoming occasion. In such situations, it is common to hear the dieter state that 1–2 lbs per week is too small for their goal.

While this is understandable, it is important to understand that scientific evidence appears to support gradual weight loss. For example, a systematic review of seven clinical trials found that, compared to rapid weight loss, gradual weight loss led to:

• Greater fat mass loss: Individuals following a steady weight loss plan lost the most total fat tissue.
• Smaller reduction in resting metabolic rate (RMR): When RMR declines, the amount of energy (calories) we burn during rest falls, which means we need a greater reduction in calories for the same degree of weight loss.

Furthermore, consistent weight loss of 1–2 lbs per week has a substantial accumulating effect. To illustrate this point, the following table shows approximately how much weight loss this weekly rate would amount to over time with consistency.

Duration	Weight loss (lbs)	Weight loss (kg)
1 month	4.3–8.6	2.0–3.9
2 months	8.6–17.2	3.9–7.8
3 months	12.9–25.8	5.9–11.7
4 months	17.2–34.4	7.8–15.6
5 months	21.5–43.0	9.8–19.5
6 months	25.8–51.6	11.7–23.5
7 months	30.1–60.2	13.7–27.4
8 months	34.4–68.8	15.6–31.2
9 months	38.7–77.4	17.6–35.2
10 months	43.0–86.0	19.5–39.1
11 months	47.3–94.6	21.5–43.0
1 year	51.7–103.2	23.5–46.9

Based on this rate of weight loss, presuming the progress was consistent, here’s how long it might take to lose specific amounts of weight:

• 5 lbs: 3–5 weeks
• 10 lbs: 5–10 weeks
• 15 lbs: 8–15 weeks
• 20 lbs: 10–20 weeks
• 30 lbs: 15–30 weeks
• 40 lbs: 20–40 weeks
• 50 lbs: 25–50 weeks

What Factors Influence the Rate of Weight Loss?

Several factors can affect how long it may take to lose weight. Understanding these can help you navigate expectations on your weight loss journey.

1. Dietary adherence
2. Energy expenditure
3. Energy intake
4. Glycogen and water weight losses
5. Medical conditions
6. Satiety
7. Starting body weight

Over the next sections, we’ll explain why these factors can have a substantial impact on weight loss within a specific timeframe.

1. Dietary Adherence

If someone follows a diet they don’t really enjoy, then periods of not adhering to it become more common, which may slow the rate of weight loss.

First of all, it’s important to follow a diet that works for you. It doesn’t matter whether that’s a Mediterranean diet, a low-carb diet, a low-fat diet, or any other dietary pattern.

In this regard, the scientific research is quite clear that adherence is a key determinant of a successful weight loss intervention.

A 2022 systematic review of randomized controlled trials found little difference in weight loss from low-fat compared to low-carb diets, with the authors noting that adherence is critical for short and long-term weight loss success.

To adhere to a diet, consider:

• Do you understand the diet?
• Do you enjoy the typical foods you are consuming on a daily and weekly basis?
• Is it sustainable?

2. Energy Expenditure

The amount of energy you expend (or the number of calories you burn) can change depending on physical activity.

Periods of greater physical activity may increase weight loss during a specific period, while prolonged inactivity may slow the rate.

3. Energy Intake

The amount of energy you consume relative to energy expenditure is the most important determinant of weight loss.

For instance, if you need to consume around 500 calories less than your energy requirements per day, exceeding or failing to meet this calorie deficit may change the rate of weight loss.

Note: If you’re unsure how many calories you need, it may be worth consulting with a dietitian if this is viable for individualized guidance. If not, the National Institutes of Health has a body weight planner which allows you to calculate your estimated calorie requirements for weight loss.

Tracking daily food intake can help you to meet calorie targets. However, it isn’t strictly necessary to count calories if you have a strong general idea of the nutritional profile of the foods you’re consuming.

Learn more: Is Counting Calories Necessary For Weight Management?

If you want to track what you are eating, there are numerous app-based options available, with MyFitnessPal being one of the best-known choices.

4. Glycogen and Water Weight

People store a form of glucose known as glycogen in the liver and muscles to provide quick energy. While total glycogen storage will differ from person to person, research has suggested people may store around 500g in the muscles and 100g in the liver.

Storing glycogen requires approximately 3–4 grams of water per gram of glycogen, so 600g glycogen could require up to 2.4 kg of water, which equates to around 3 kg of stored weight.

However, glycogen levels fall when we use glycogen for exercise without adequately replacing it through carbohydrate intake. A diet that leads to consistent weight loss may also deplete glycogen stores.

The point here is that the initial weight loss from following a diet could be influenced by losses of glycogen and water weight, so the initial losses may seem more pronounced.

It is important to be aware of this as some dieters may feel enthusiastic after seeing such rapid initial weight loss, only to be disappointed when the rate of weight loss slows once glycogen stores have fallen.

5. Medical Conditions

It is possible for medical conditions to affect the rate of weight loss.

For example, some conditions like specific cancers may increase the metabolic rate, causing the body to burn a larger number of calories.

If you have a medical condition and are embarking on a new diet, please consult your healthcare provider for relevant, individualized guidance.

6. Satiety

In recent decades, the role that satiety plays in weight loss interventions has become more widely recognized. Satiety refers to the feeling of being satisfied or full after a meal, without feeling an urge to eat more food.

While satiety doesn’t directly impact weight loss rates, it can potentially do so indirectly by how it interacts with adherence. For example, if you are following a diet that always leaves you feeling hungry and wanting more food, the chances of long-term adherence will likely be lower.

Systematic reviews have linked foods high in cereal fiber as well as protein-rich diets with higher satiety levels.

Other factors thought to contribute to satiety include whole foods with a high volume. For instance, whole apples contain fiber and water, and they are thought to better contribute to satiety than apple juice, which lacks the fiber and volume-per-calorie of whole apples.

Learn more about satiety: What Is the Satiety Index of Common Foods?

7. Starting Body Weight

Lastly, an individual’s body weight at the start of a diet can influence the potential rate of weight loss.

For example, if someone weighs 300 lbs (136 kg), their energy requirements will be much higher than someone weighing 200 lbs (91 kg).

This may make it easier for them to lose weight faster at first if they are eating (and able to maintain) a similar total calorie target.

Summary

As the evidence shows, weight loss rates can vary depending on factors like adherence, starting body weight, and more. For most people, guidance advises a steady rate of around 1–2 lbs per week.

Quick-fix solutions such as extreme, unsustainable diets, as well as many weight loss supplements, are unlikely to provide long-lasting results.

What should come first is a sensible and nutrient-rich dietary plan that you actually enjoy. Enjoying the way you eat increases the likelihood of sustaining the diet in the longer term, which can decrease how long it takes to lose a desired amount of weight.

Lastly, never be afraid of seeking advice for weight management issues. Many people live with overweight or obesity, and there is no shame in this or in wanting to lose weight.

References